Internationalization + Finnish language (#181)

* I18n with next-intl

* package-lock

* Finnish translations

* Development fix

* Use locale for positioning currency symbol

* Translations: Expenses.ActiveUserModal

* Translations: group 404

* Better translation for ExpenseCard

* Apply translations in CategorySelect search

* Fix for Finnish translation

* Translations for ExpenseDocumentsInput

* Translations for CreateFromReceipt

* Fix for Finnish translation

* Translations for schema errors

* Fix for Finnish translation

* Fixes for Finnish translations

* Prettier

---------

Co-authored-by: Sebastien Castiel <sebastien@castiel.me>

messages/en-US.json

@@ -0,0 +1,374 @@
+{
+  "Header": {
+    "groups": "Groups"
+  },
+  "Footer": {
+    "madeIn": "Made in Montréal, Québec 🇨🇦",
+    "builtBy": "Built by <author>Sebastien Castiel</author> and <source>contributors</source>"
+  },
+  "Expenses": {
+    "title": "Expenses",
+    "description": "Here are the expenses that you created for your group.",
+    "create": "Create expense",
+    "createFirst": "Create the first one",
+    "noExpenses": "Your group doesn’t contain any expense yet.",
+    "exportJson": "Export to JSON",
+    "searchPlaceholder": "Search for an expense…",
+    "ActiveUserModal": {
+      "title": "Who are you?",
+      "description": "Tell us which participant you are to let us customize how the information is displayed.",
+      "nobody": "I don’t want to select anyone",
+      "save": "Save changes",
+      "footer": "This setting can be changed later in the group settings."
+    },
+    "Groups": {
+      "upcoming": "Upcoming",
+      "thisWeek": "This week",
+      "earlierThisMonth": "Earlier this month",
+      "lastMonth": "Last month",
+      "earlierThisYear": "Earlier this year",
+      "lastYera": "Last year",
+      "older": "Older"
+    }
+  },
+  "ExpenseCard": {
+    "paidBy": "Paid by <strong>{paidBy}</strong> for <paidFor></paidFor>",
+    "receivedBy": "Received by <strong>{paidBy}</strong> for <paidFor></paidFor>",
+    "yourBalance": "Your balance:"
+  },
+  "Groups": {
+    "myGroups": "My groups",
+    "create": "Create",
+    "loadingRecent": "Loading recent groups…",
+    "NoRecent": {
+      "description": "You have not visited any group recently.",
+      "create": "Create one",
+      "orAsk": "or ask a friend to send you the link to an existing one."
+    },
+    "recent": "Recent groups",
+    "starred": "Starred groups",
+    "archived": "Archived groups",
+    "archive": "Archive group",
+    "unarchive": "Unarchive group",
+    "removeRecent": "Remove from recent groups",
+    "RecentRemovedToast": {
+      "title": "Group has been removed",
+      "description": "The group was removed from your recent groups list.",
+      "undoAlt": "Undo group removal",
+      "undo": "Undo"
+    },
+    "AddByURL": {
+      "button": "Add by URL",
+      "title": "Add a group by URL",
+      "description": "If a group was shared with you, you can paste its URL here to add it to your list.",
+      "error": "Oops, we are not able to find the group from the URL you provided…"
+    },
+    "NotFound": {
+      "text": "This group does not exist.",
+      "link": "Go to recently visited groups"
+    }
+  },
+  "GroupForm": {
+    "title": "Group information",
+    "NameField": {
+      "label": "Group name",
+      "placeholder": "Summer vacations",
+      "description": "Enter a name for your group."
+    },
+    "CurrencyField": {
+      "label": "Currency symbol",
+      "placeholder": "$, €, £…",
+      "description": "We’ll use it to display amounts."
+    },
+    "Participants": {
+      "title": "Participants",
+      "description": "Enter the name for each participant.",
+      "protectedParticipant": "This participant is part of expenses, and can not be removed.",
+      "new": "New",
+      "add": "Add participant",
+      "John": "John",
+      "Jane": "Jane",
+      "Jack": "Jack"
+    },
+    "Settings": {
+      "title": "Local settings",
+      "description": "These settings are set per-device, and are used to customize your experience.",
+      "ActiveUserField": {
+        "label": "Active user",
+        "placeholder": "Select a participant",
+        "none": "None",
+        "description": "User used as default for paying expenses."
+      },
+      "save": "Save",
+      "saving": "Saving…",
+      "create": "Create",
+      "creating": "Creating…",
+      "cancel": "Cancel"
+    }
+  },
+  "ExpenseForm": {
+    "Income": {
+      "create": "Create income",
+      "edit": "Edit income",
+      "TitleField": {
+        "label": "Income title",
+        "placeholder": "Monday evening restaurant",
+        "description": "Enter a description for the income."
+      },
+      "DateField": {
+        "label": "Income date",
+        "description": "Enter the date the income was received."
+      },
+      "categoryFieldDescription": "Select the income category.",
+      "paidByField": {
+        "label": "Received by",
+        "description": "Select the participant who received the income."
+      },
+      "paidFor": {
+        "title": "Received for",
+        "description": "Select who the income was received for."
+      },
+      "splitModeDescription": "Select how to split the income.",
+      "attachDescription": "See and attach receipts to the income."
+    },
+    "Expense": {
+      "create": "Create expense",
+      "edit": "Edit expense",
+      "TitleField": {
+        "label": "Expense title",
+        "placeholder": "Monday evening restaurant",
+        "description": "Enter a description for the expense."
+      },
+      "DateField": {
+        "label": "Expense date",
+        "description": "Enter the date the expense was paid."
+      },
+      "categoryFieldDescription": "Select the expense category.",
+      "paidByField": {
+        "label": "Paid by",
+        "description": "Select the participant who paid the expense."
+      },
+      "paidFor": {
+        "title": "Paid for",
+        "description": "Select who the expense was paid for."
+      },
+      "splitModeDescription": "Select how to split the expense.",
+      "attachDescription": "See and attach receipts to the expense."
+    },
+    "amountField": {
+      "label": "Amount"
+    },
+    "isReimbursementField": {
+      "label": "This is a reimbursement"
+    },
+    "categoryField": {
+      "label": "Category"
+    },
+    "notesField": {
+      "label": "Notes"
+    },
+    "selectNone": "Select none",
+    "selectAll": "Select all",
+    "shares": "share(s)",
+    "advancedOptions": "Advanced splitting options…",
+    "SplitModeField": {
+      "label": "Split mode",
+      "evenly": "Evenly",
+      "byShares": "Unevenly – By shares",
+      "byPercentage": "Unevenly – By percentage",
+      "byAmount": "Unevenly – By amount",
+      "saveAsDefault": "Save as default splitting options"
+    },
+    "DeletePopup": {
+      "label": "Delete",
+      "title": "Delete this expense?",
+      "description": "Do you really want to delete this expense? This action is irreversible.",
+      "yes": "Yes",
+      "cancel": "Cancel"
+    },
+    "attachDocuments": "Attach documents",
+    "create": "Create",
+    "creating": "Creating…",
+    "save": "Save",
+    "saving": "Saving…",
+    "cancel": "Cancel"
+  },
+  "ExpenseDocumentsInput": {
+    "TooBigToast": {
+      "title": "The file is too big",
+      "description": "The maximum file size you can upload is {maxSize}. Yours is ${size}."
+    },
+    "ErrorToast": {
+      "title": "Error while uploading document",
+      "description": "Something wrong happened when uploading the document. Please retry later or select a different file.",
+      "retry": "Retry"
+    }
+  },
+  "CreateFromReceipt": {
+    "Dialog": {
+      "triggerTitle": "Create expense from receipt",
+      "title": "Create from receipt",
+      "description": "Extract the expense information from a receipt photo.",
+      "body": "Upload the photo of a receipt, and we’ll scan it to extract the expense information if we can.",
+      "selectImage": "Select image…",
+      "titleLabel": "Title:",
+      "categoryLabel": "Category:",
+      "amountLabel": "Amount:",
+      "dateLabel": "Date:",
+      "editNext": "You’ll be able to edit the expense information next.",
+      "continue": "Continue"
+    },
+    "unknown": "Unknown",
+    "TooBigToast": {
+      "title": "The file is too big",
+      "description": "The maximum file size you can upload is {maxSize}. Yours is ${size}."
+    },
+    "ErrorToast": {
+      "title": "Error while uploading document",
+      "description": "Something wrong happened when uploading the document. Please retry later or select a different file.",
+      "retry": "Retry"
+    }
+  },
+  "Balances": {
+    "title": "Balances",
+    "description": "This is the amount that each participant paid or was paid for.",
+    "Reimbursements": {
+      "title": "Suggested reimbursements",
+      "description": "Here are suggestions for optimized reimbursements between participants.",
+      "noImbursements": "It looks like your group doesn’t need any reimbursement 😁",
+      "owes": "<strong>{from}</strong> owes <strong>{to}</strong>",
+      "markAsPaid": "Mark as paid"
+    }
+  },
+  "Stats": {
+    "title": "Stats",
+    "Totals": {
+      "title": "Totals",
+      "description": "Spending summary of the entire group.",
+      "groupSpendings": "Total group spendings",
+      "groupEarnings": "Total group earnings",
+      "yourSpendings": "Your total spendings",
+      "yourEarnings": "Your total earnings",
+      "yourShare": "Your total share"
+    }
+  },
+  "Activity": {
+    "title": "Activity",
+    "description": "Overview of all activity in this group.",
+    "noActivity": "There is not yet any activity in your group.",
+    "someone": "Someone",
+    "settingsModified": "Group settings were modified by <strong>{participant}</strong>.",
+    "expenseCreated": "Expense <em>{expense}</em> created by <strong>{participant}</strong>.",
+    "expenseUpdated": "Expense <em>{expense}</em> updated by <strong>{participant}</strong>.",
+    "expenseDeleted": "Expense <em>{expense}</em> deleted by <strong>{participant}</strong>.",
+    "Groups": {
+      "today": "Today",
+      "yesterday": "Yesterday",
+      "earlierThisWeek": "Earlier this week",
+      "lastWeek": "Last week",
+      "earlierThisMonth": "Earlier this month",
+      "lastMonth": "Last month",
+      "earlierThisYear": "Earlier this year",
+      "lastYear": "Last year",
+      "older": "Older"
+    }
+  },
+  "Settings": {
+    "title": "Settings"
+  },
+  "Locale": {
+    "en-US": "English (US)",
+    "fi": "Suomi"
+  },
+  "Share": {
+    "title": "Share",
+    "description": "For other participants to see the group and add expenses, share its URL with them.",
+    "warning": "Warning!",
+    "warningHelp": "Every person with the group URL will be able to see and edit expenses. Share with caution!"
+  },
+  "SchemaErrors": {
+    "min1": "Enter at least one character.",
+    "min2": "Enter at least two characters.",
+    "max5": "Enter at most five characters.",
+    "max50": "Enter at most 50 characters.",
+    "duplicateParticipantName": "Another participant already has this name.",
+    "titleRequired": "Please enter a title.",
+    "invalidNumber": "Invalid number.",
+    "amountRequired": "You must enter an amount.",
+    "amountNotZero": "The amount must not be zero.",
+    "amountTenMillion": "The amount must be lower than 10,000,000.",
+    "paidByRequired": "You must select a participant.",
+    "paidForMin1": "The expense must be paid for at least one participant.",
+    "noZeroShares": "All shares must be higher than 0.",
+    "amountSum": "Sum of amounts must equal the expense amount.",
+    "percentageSum": "Sum of percentages must equal 100."
+  },
+  "Categories": {
+    "search": "Search category...",
+    "noCategory": "No category found.",
+    "Uncategorized": {
+      "heading": "Uncategorized",
+      "General": "General",
+      "Payment": "Payment"
+    },
+    "Entertainment": {
+      "heading": "Entertainment",
+      "Entertainment": "Entertainment",
+      "Games": "Games",
+      "Movies": "Movies",
+      "Music": "Music",
+      "Sports": "Sports"
+    },
+    "Food and Drink": {
+      "heading": "Food and Drink",
+      "Food and Drink": "Food and Drink",
+      "Dining Out": "Dining Out",
+      "Groceries": "Groceries",
+      "Liquor": "Liquor"
+    },
+    "Home": {
+      "heading": "Home",
+      "Home": "Home",
+      "Electronics": "Electronics",
+      "Furniture": "Furniture",
+      "Household Supplies": "Household Supplies",
+      "Maintenance": "Maintenance",
+      "Mortgage": "Mortgage",
+      "Pets": "Pets",
+      "Rent": "Rent",
+      "Services": "Services"
+    },
+    "Life": {
+      "heading": "Life",
+      "Childcare": "Childcare",
+      "Clothing": "Clothing",
+      "Education": "Education",
+      "Gifts": "Gifts",
+      "Insurance": "Insurance",
+      "Medical Expenses": "Medical Expenses",
+      "Taxes": "Taxes"
+    },
+    "Transportation": {
+      "heading": "Transportation",
+      "Transportation": "Transportation",
+      "Bicycle": "Bicycle",
+      "Bus/Train": "Bus/Train",
+      "Car": "Car",
+      "Gas/Fuel": "Gas/Fuel",
+      "Hotel": "Hotel",
+      "Parking": "Parking",
+      "Plane": "Plane",
+      "Taxi": "Taxi"
+    },
+    "Utilities": {
+      "heading": "Utilities",
+      "Utilities": "Utilities",
+      "Cleaning": "Cleaning",
+      "Electricity": "Electricity",
+      "Heat/Gas": "Heat/Gas",
+      "Trash": "Trash",
+      "TV/Phone/Internet": "TV/Phone/Internet",
+      "Water": "Water"
+    }
+  }
+}

messages/fi.json

@@ -0,0 +1,374 @@
+{
+  "Header": {
+    "groups": "Ryhmät"
+  },
+  "Footer": {
+    "madeIn": "Made in Montréal, Québec 🇨🇦",
+    "builtBy": "Tekijät: <author>Sebastien Castiel</author> ja <source>muut osallistujat</source>"
+  },
+  "Expenses": {
+    "title": "Kulut",
+    "description": "Tässä ovat ryhmässä luodut kulut.",
+    "create": "Lisää kulu",
+    "createFirst": "Lisää ensimmäinen kulu",
+    "noExpenses": "Ryhmälläsi ei ole vielä yhtään kulua.",
+    "exportJson": "Vie JSON-tiedostoon",
+    "searchPlaceholder": "Etsi kulua…",
+    "ActiveUserModal": {
+      "title": "Kuka olet?",
+      "description": "Valitse kuka osallistujista olet, jotta tiedot näkyvät oikein.",
+      "nobody": "En halua valita ketään",
+      "save": "Tallenna muutokset",
+      "footer": "Tämän asetuksen voi vaihtaa myöhemmin ryhmän asetuksista."
+    },
+    "Groups": {
+      "upcoming": "Tulevat",
+      "thisWeek": "Tällä viikolla",
+      "earlierThisMonth": "Aikaisemmin tässä kuussa",
+      "lastMonth": "Viime kuussa",
+      "earlierThisYear": "Aikaisemmin tänä vuonna",
+      "lastYear": "Viime vuonna",
+      "older": "Vanhemmat"
+    }
+  },
+  "ExpenseCard": {
+    "paidBy": "<strong>{paidBy}</strong> maksoi {forCount, plural, =1 {henkilön} other {henkilöiden}} <paidFor></paidFor> puolesta",
+    "receivedBy": "<strong>{paidBy}</strong> sai rahaa {forCount, plural, =1 {henkilön} other {henkilöiden}} <paidFor></paidFor> puolesta",
+    "yourBalance": "Saldosi:"
+  },
+  "Groups": {
+    "myGroups": "Omat ryhmät",
+    "create": "Luo ryhmä",
+    "loadingRecent": "Ladataan äskettäisiä ryhmiä…",
+    "NoRecent": {
+      "description": "Et ole ollut missään ryhmässä äskettäin.",
+      "create": "Luo uusi ryhmä",
+      "orAsk": "tai pyydä ystävää lähettämään linkki olemassaolevaan ryhmään."
+    },
+    "recent": "Äskettäiset",
+    "starred": "Suosikit",
+    "archived": "Arkistoidut",
+    "archive": "Arkistoi ryhmä",
+    "unarchive": "Palauta ryhmä arkistosta",
+    "removeRecent": "Poista äskettäisistä",
+    "RecentRemovedToast": {
+      "title": "Ryhmä poistettu",
+      "description": "Ryhmä poistettu äskettäisten listaltasi.",
+      "undoAlt": "Peruuta ryhmän poisto",
+      "undo": "Peruuta"
+    },
+    "AddByURL": {
+      "button": "Lisää URLilla",
+      "title": "Lisää ryhmä URL-osoitteella",
+      "description": "Jos ryhmä on jaettu sinulle, voit lisätä sen listaasi liittämällä URL-osoitteen tähän.",
+      "error": "Hups, emme löytäneet ryhmää antamastasi URL-osoitteesta…"
+    },
+    "NotFound": {
+      "text": "Tätä ryhmää ei löydy.",
+      "link": "Siirry äskettäisiin ryhmiin"
+    }
+  },
+  "GroupForm": {
+    "title": "Ryhmän tiedot",
+    "NameField": {
+      "label": "Ryhmän nimi",
+      "placeholder": "Kesälomareissu",
+      "description": "Syötä ryhmäsi nimi."
+    },
+    "CurrencyField": {
+      "label": "Valuuttamerkki",
+      "placeholder": "$, €, £…",
+      "description": "Näytetään rahasummien yhteydessä."
+    },
+    "Participants": {
+      "title": "Osallistujat",
+      "description": "Syötä jokaisen osallistujan nimi.",
+      "protectedParticipant": "Tätä osallistujaa ei voida poistaa, koska hän osallistuu kuluihin.",
+      "add": "Lisää osallistuja",
+      "new": "Uusi",
+      "John": "Antti",
+      "Jane": "Laura",
+      "Jack": "Jussi"
+    },
+    "Settings": {
+      "title": "Paikalliset asetukset",
+      "description": "Nämä asetukset ovat laitekohtaisia. Voit muokata niillä käytettävyyttä.",
+      "ActiveUserField": {
+        "label": "Aktiivinen käyttäjä",
+        "placeholder": "Valitse osallistuja",
+        "none": "Ei kukaan",
+        "description": "Käytetään kulujen oletusmaksajana."
+      },
+      "save": "Tallenna",
+      "saving": "Tallennetaan…",
+      "create": "Luo ryhmä",
+      "creating": "Luodaan…",
+      "cancel": "Peruuta"
+    }
+  },
+  "ExpenseForm": {
+    "Income": {
+      "create": "Lisää tulo",
+      "edit": "Muokkaa tuloa",
+      "TitleField": {
+        "label": "Otsikko",
+        "placeholder": "Maanantain ravintola",
+        "description": "Anna lyhyt kuvaus tulolle."
+      },
+      "DateField": {
+        "label": "Päivä",
+        "description": "Valitse päivä jolloin tulo saatiin."
+      },
+      "categoryFieldDescription": "Valitse tulokategoria.",
+      "paidByField": {
+        "label": "Vastaanottaja",
+        "description": "Valitse kuka vastaanotti tulon."
+      },
+      "paidFor": {
+        "title": "Tulon jakaminen",
+        "description": "Valitse kenelle tulo jaetaan."
+      },
+      "splitModeDescription": "Valitse miten tulo jaetaan osallistujien kesken.",
+      "attachDescription": "Katso ja liitä tuloon liittyviä kuitteja."
+    },
+    "Expense": {
+      "create": "Lisää kulu",
+      "edit": "Muokkaa kulua",
+      "TitleField": {
+        "label": "Otsikko",
+        "placeholder": "Maanantain ravintola",
+        "description": "Anna lyhyt kuvaus kululle."
+      },
+      "DateField": {
+        "label": "Päivä",
+        "description": "Valitse päivä jolloin kulu maksettiin."
+      },
+      "categoryFieldDescription": "Valitse kulukategoria.",
+      "paidByField": {
+        "label": "Maksaja",
+        "description": "Valitse kuka maksoi kulun."
+      },
+      "paidFor": {
+        "title": "Kulun jakaminen",
+        "description": "Valitse ketkä osallistuvat kuluun."
+      },
+      "splitModeDescription": "Valitse miten kulu jaetaan osallistujien kesken.",
+      "attachDescription": "Katso ja liitä kuluun liittyviä kuitteja."
+    },
+    "amountField": {
+      "label": "Summa"
+    },
+    "isReimbursementField": {
+      "label": "Tämä on velanmaksu"
+    },
+    "categoryField": {
+      "label": "Kategoria"
+    },
+    "notesField": {
+      "label": "Muistiinpanot"
+    },
+    "selectNone": "Tyhjennä valinnat",
+    "selectAll": "Valitse kaikki",
+    "shares": "osuutta",
+    "advancedOptions": "Lisäasetuksia jakamiseen…",
+    "SplitModeField": {
+      "label": "Jakamistapa",
+      "evenly": "Tasan",
+      "byShares": "Epätasan – osuuksien mukaan",
+      "byPercentage": "Epätasan – prosenttien mukaan",
+      "byAmount": "Epätasan – summan mukaan",
+      "saveAsDefault": "Tallenna oletustavaksi"
+    },
+    "DeletePopup": {
+      "label": "Poista",
+      "title": "Poistetaanko tämä kulu?",
+      "description": "Haluatko varmasti poistaa tämän kulun? Poistoa ei voi peruuttaa.",
+      "yes": "Kyllä",
+      "cancel": "Peruuta"
+    },
+    "attachDocuments": "Liitä dokumenttejä",
+    "create": "Lisää kulu",
+    "creating": "Luodaan kulua…",
+    "save": "Tallenna",
+    "saving": "Tallennetaan…",
+    "cancel": "Peruuta"
+  },
+  "ExpenseDocumentsInput": {
+    "TooBigToast": {
+      "title": "Tiedosto on liian suuri",
+      "description": "Maksimikoko ladattavalle tiedostolle on {maxSize}. Tiedostosi on ${size}."
+    },
+    "ErrorToast": {
+      "title": "Virhe tiedostoa ladattaessa",
+      "description": "Jokin meni vikaan dokumentin lataamisessa. Yritä myöhemmin uudelleen tai valitse toinen tiedosto.",
+      "retry": "Yritä uudelleen"
+    }
+  },
+  "CreateFromReceipt": {
+    "Dialog": {
+      "triggerTitle": "Luo kulu kuitista",
+      "title": "Luo kuitista",
+      "description": "Lue kuitin valokuvasta kulun tiedot.",
+      "body": "Lataa kuitista valokuva. Siitä skannataan tiedot kulua varten.",
+      "selectImage": "Valitse kuva…",
+      "titleLabel": "Otsikko:",
+      "categoryLabel": "Kategoria:",
+      "amountLabel": "Summa:",
+      "dateLabel": "Päivä:",
+      "editNext": "Voit muokata kulun tietoja seuraavaksi.",
+      "continue": "Jatka"
+    },
+    "unknown": "Unknown",
+    "TooBigToast": {
+      "title": "The file is too big",
+      "description": "The maximum file size you can upload is {maxSize}. Yours is ${size}."
+    },
+    "ErrorToast": {
+      "title": "Error while uploading document",
+      "description": "Something wrong happened when uploading the document. Please retry later or select a different file.",
+      "retry": "Retry"
+    }
+  },
+  "Balances": {
+    "title": "Saldo",
+    "description": "Osallistujien saatavat tai velat.",
+    "Reimbursements": {
+      "title": "Maksuehdotus",
+      "description": "Optimoitu ehdotus kuka maksaa kenellekin.",
+      "noImbursements": "Näyttää siltä, että kaikki ovat sujut 😁",
+      "owes": "<strong>{from}</strong> maksaa henkilölle <strong>{to}</strong>",
+      "markAsPaid": "Merkitse maksetuksi"
+    }
+  },
+  "Stats": {
+    "title": "Tilastot",
+    "Totals": {
+      "title": "Yhteenveto",
+      "description": "Koko ryhmän kulut.",
+      "groupSpendings": "Koko ryhmän kulutus",
+      "groupEarnings": "Koko ryhmän saatavat",
+      "yourSpendings": "Kulutuksesi",
+      "yourEarnings": "Saatavasi",
+      "yourShare": "Osuutesi"
+    }
+  },
+  "Activity": {
+    "title": "Tapahtumat",
+    "description": "Yleisnäkymä ryhmän kaikista tapahtumista.",
+    "noActivity": "Ryhmässäsi ei ole vielä tapahtumia.",
+    "someone": "Tuntematon",
+    "settingsModified": "<strong>{participant}</strong> muokkasi ryhmän asetuksia.",
+    "expenseCreated": "<strong>{participant}</strong> lisäsi kulun <em>{expense}</em>.",
+    "expenseUpdated": "<strong>{participant}</strong> muokkasi kulua <em>{expense}</em>.",
+    "expenseDeleted": "<strong>{participant}</strong> poisti kulun <em>{expense}</em>.",
+    "Groups": {
+      "today": "Tänään",
+      "yesterday": "Eilen",
+      "earlierThisWeek": "Tällä viikolla",
+      "lastWeek": "Viime viikolla",
+      "earlierThisMonth": "Tässä kuussa",
+      "lastMonth": "Viime kuussa",
+      "earlierThisYear": "Tänä vuonna",
+      "lastYear": "Viime vuonna",
+      "older": "Vanhemmat"
+    }
+  },
+  "Settings": {
+    "title": "Asetukset"
+  },
+  "Locale": {
+    "en-US": "English (US)",
+    "fi": "Suomi"
+  },
+  "Share": {
+    "title": "Jaa",
+    "description": "Jaa ryhmän URL muille jäsenille, jotta he voivat nähdä sen ja lisätä kuluja.",
+    "warning": "Varoitus!",
+    "warningHelp": "Tällä URLilla kuka tahansa pääsee näkemään ja muokkaamaan kuluja. Jaa harkiten!"
+  },
+  "SchemaErrors": {
+    "min1": "Syötä vähintään yksi merkki.",
+    "min2": "Syötä vähintään kaksi merkkiä.",
+    "max5": "Syötä enintään viisi merkkiä.",
+    "max50": "Syötä enintään 50 merkkiä.",
+    "duplicateParticipantName": "Tämä nimi on jo toisella osallistujalla.",
+    "titleRequired": "Otsikko puuttuu.",
+    "invalidNumber": "Epäkelpo numero.",
+    "amountRequired": "Summa puuttuu.",
+    "amountNotZero": "Summa ei voi olla nolla.",
+    "amountTenMillion": "Summan pitää olla pienempi kuin 10 000 000.",
+    "paidByRequired": "Osallistuja puuttuu.",
+    "paidForMin1": "Valitse vähintään yksi osallistuja.",
+    "noZeroShares": "Jokaisen osuuden täytyy olla suurempi kuin 0.",
+    "amountSum": "Osuuksien summan täytyy vastata kulun summaa.",
+    "percentageSum": "Prosenttiosuuksien summan täytyy olla 100."
+  },
+  "Categories": {
+    "search": "Etsi kategoriaa...",
+    "noCategory": "Kategoriaa ei löydy.",
+    "Uncategorized": {
+      "heading": "Yleiset",
+      "General": "Yleinen",
+      "Payment": "Maksu"
+    },
+    "Entertainment": {
+      "heading": "Viihde",
+      "Entertainment": "Viihde",
+      "Games": "Pelit",
+      "Movies": "Elokuvat",
+      "Music": "Musiikki",
+      "Sports": "Urheilu"
+    },
+    "Food and Drink": {
+      "heading": "Ruoka ja juoma",
+      "Food and Drink": "Ruoka ja juoma",
+      "Dining Out": "Ulkona syöminen",
+      "Groceries": "Marketti",
+      "Liquor": "Alkoholi"
+    },
+    "Home": {
+      "heading": "Koti",
+      "Home": "Koti",
+      "Electronics": "Elektroniikka",
+      "Furniture": "Huonekalut",
+      "Household Supplies": "Taloustavarat",
+      "Maintenance": "Huolto",
+      "Mortgage": "Laina",
+      "Pets": "Lemmikit",
+      "Rent": "Vuokra",
+      "Services": "Palvelut"
+    },
+    "Life": {
+      "heading": "Elämä",
+      "Childcare": "Lastenhoito",
+      "Clothing": "Vaatteet",
+      "Education": "Opiskelu",
+      "Gifts": "Lahjat",
+      "Insurance": "Vakuutukset",
+      "Medical Expenses": "Terveydenhoito",
+      "Taxes": "Verot"
+    },
+    "Transportation": {
+      "heading": "Liikenne",
+      "Transportation": "Liikenne",
+      "Bicycle": "Polkupyörä",
+      "Bus/Train": "Bussi/juna",
+      "Car": "Auto",
+      "Gas/Fuel": "Polttoaine",
+      "Hotel": "Hotelli",
+      "Parking": "Pysäköinti",
+      "Plane": "Lentäminen",
+      "Taxi": "Taksi"
+    },
+    "Utilities": {
+      "heading": "Sekalaiset",
+      "Utilities": "Sekalaiset",
+      "Cleaning": "Siivous",
+      "Electricity": "Sähkö",
+      "Heat/Gas": "Lämmitys",
+      "Trash": "Jätehuolto",
+      "TV/Phone/Internet": "TV/Puhelin/Internet",
+      "Water": "Vesi"
+    }
+  }
+}

next.config.mjs

@@ -1,4 +1,8 @@
-/** 
+import createNextIntlPlugin from 'next-intl/plugin'
+
+const withNextIntl = createNextIntlPlugin()
+
+/**
  * Undefined entries are not supported. Push optional patterns to this array only if defined.
  * @type {import('next/dist/shared/lib/image-config').RemotePattern}
  */
@@ -31,4 +35,4 @@ const nextConfig = {
 },
 }
 
-module.exports = nextConfig
+export default withNextIntl(nextConfig)

package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.1.0",
       "hasInstallScript": true,
       "dependencies": {
+        "@formatjs/intl-localematcher": "^0.5.4",
         "@hookform/resolvers": "^3.3.2",
         "@prisma/client": "^5.6.0",
         "@radix-ui/react-checkbox": "^1.0.4",
@@ -33,7 +34,9 @@
         "embla-carousel-react": "^8.0.0-rc21",
         "lucide-react": "^0.290.0",
         "nanoid": "^5.0.4",
+        "negotiator": "^0.6.3",
         "next": "^14.2.3",
+        "next-intl": "^3.17.2",
         "next-s3-upload": "^0.3.4",
         "next-themes": "^0.2.1",
         "next13-progressbar": "^1.1.1",
@@ -55,6 +58,7 @@
       "devDependencies": {
         "@total-typescript/ts-reset": "^0.5.1",
         "@types/content-disposition": "^0.5.8",
+        "@types/negotiator": "^0.6.3",
         "@types/node": "^20",
         "@types/pg": "^8.10.9",
         "@types/react": "^18.2.48",
@@ -1006,6 +1010,50 @@
       "resolved": "https://registry.npmjs.org/@floating-ui/utils/-/utils-0.1.6.tgz",
       "integrity": "sha512-OfX7E2oUDYxtBvsuS4e/jSn4Q9Qb6DzgeYtsAdkPZ47znpoNsMgZw0+tVijiv3uGNR6dgNlty6r9rzIzHjtd/A=="
     },
+    "node_modules/@formatjs/ecma402-abstract": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@formatjs/ecma402-abstract/-/ecma402-abstract-2.0.0.tgz",
+      "integrity": "sha512-rRqXOqdFmk7RYvj4khklyqzcfQl9vEL/usogncBHRZfZBDOwMGuSRNFl02fu5KGHXdbinju+YXyuR+Nk8xlr/g==",
+      "dependencies": {
+        "@formatjs/intl-localematcher": "0.5.4",
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@formatjs/fast-memoize": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/@formatjs/fast-memoize/-/fast-memoize-2.2.0.tgz",
+      "integrity": "sha512-hnk/nY8FyrL5YxwP9e4r9dqeM6cAbo8PeU9UjyXojZMNvVad2Z06FAVHyR3Ecw6fza+0GH7vdJgiKIVXTMbSBA==",
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@formatjs/icu-messageformat-parser": {
+      "version": "2.7.8",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-messageformat-parser/-/icu-messageformat-parser-2.7.8.tgz",
+      "integrity": "sha512-nBZJYmhpcSX0WeJ5SDYUkZ42AgR3xiyhNCsQweFx3cz/ULJjym8bHAzWKvG5e2+1XO98dBYC0fWeeAECAVSwLA==",
+      "dependencies": {
+        "@formatjs/ecma402-abstract": "2.0.0",
+        "@formatjs/icu-skeleton-parser": "1.8.2",
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@formatjs/icu-skeleton-parser": {
+      "version": "1.8.2",
+      "resolved": "https://registry.npmjs.org/@formatjs/icu-skeleton-parser/-/icu-skeleton-parser-1.8.2.tgz",
+      "integrity": "sha512-k4ERKgw7aKGWJZgTarIcNEmvyTVD9FYh0mTrrBMHZ1b8hUu6iOJ4SzsZlo3UNAvHYa+PnvntIwRPt1/vy4nA9Q==",
+      "dependencies": {
+        "@formatjs/ecma402-abstract": "2.0.0",
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@formatjs/intl-localematcher": {
+      "version": "0.5.4",
+      "resolved": "https://registry.npmjs.org/@formatjs/intl-localematcher/-/intl-localematcher-0.5.4.tgz",
+      "integrity": "sha512-zTwEpWOzZ2CiKcB93BLngUX59hQkuZjT2+SAQEscSm52peDW/getsawMcWF1rGRpMCX6D7nSJA3CzJ8gn13N/g==",
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
     "node_modules/@hookform/resolvers": {
       "version": "3.3.2",
       "resolved": "https://registry.npmjs.org/@hookform/resolvers/-/resolvers-3.3.2.tgz",
@@ -3116,6 +3164,12 @@
       "integrity": "sha512-dRLjCWHYg4oaA77cxO64oO+7JwCwnIzkZPdrrC71jQmQtlhM556pwKo5bUzqvZndkVbeFLIIi+9TC40JNF5hNQ==",
       "dev": true
     },
+    "node_modules/@types/negotiator": {
+      "version": "0.6.3",
+      "resolved": "https://registry.npmjs.org/@types/negotiator/-/negotiator-0.6.3.tgz",
+      "integrity": "sha512-JkXTOdKs5MF086b/pt8C3+yVp3iDUwG635L7oCH6HvJvvr6lSUU5oe/gLXnPEfYRROHjJIPgCV6cuAg8gGkntQ==",
+      "dev": true
+    },
     "node_modules/@types/node": {
       "version": "20.8.9",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-20.8.9.tgz",
@@ -5837,6 +5891,17 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/intl-messageformat": {
+      "version": "10.5.14",
+      "resolved": "https://registry.npmjs.org/intl-messageformat/-/intl-messageformat-10.5.14.tgz",
+      "integrity": "sha512-IjC6sI0X7YRjjyVH9aUgdftcmZK7WXdHeil4KwbjDnRWjnVitKpAx3rr6t6di1joFp5188VqKcobOPA6mCLG/w==",
+      "dependencies": {
+        "@formatjs/ecma402-abstract": "2.0.0",
+        "@formatjs/fast-memoize": "2.2.0",
+        "@formatjs/icu-messageformat-parser": "2.7.8",
+        "tslib": "^2.4.0"
+      }
+    },
     "node_modules/invariant": {
       "version": "2.2.4",
       "resolved": "https://registry.npmjs.org/invariant/-/invariant-2.2.4.tgz",
@@ -6577,6 +6642,14 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/negotiator": {
+      "version": "0.6.3",
+      "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-0.6.3.tgz",
+      "integrity": "sha512-+EUsqGPLsM+j/zdChZjsnX51g4XrHFOIXwfnCVPGlQk/k5giakcKsuxCObBRu6DSm9opw/O6slWbJdghQM4bBg==",
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
     "node_modules/next": {
       "version": "14.2.3",
       "resolved": "https://registry.npmjs.org/next/-/next-14.2.3.tgz",
@@ -6626,6 +6699,34 @@
         }
       }
     },
+    "node_modules/next-intl": {
+      "version": "3.17.2",
+      "resolved": "https://registry.npmjs.org/next-intl/-/next-intl-3.17.2.tgz",
+      "integrity": "sha512-X2ly23e1lC5vdWHaJFBDZi/0iornEdFQQtqJmmPOb7WD+LDssm9vAnx+hJshYGjddaP3rUmyWaPgePCQqaxm1g==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/amannn"
+        }
+      ],
+      "dependencies": {
+        "@formatjs/intl-localematcher": "^0.2.32",
+        "negotiator": "^0.6.3",
+        "use-intl": "^3.17.2"
+      },
+      "peerDependencies": {
+        "next": "^10.0.0 || ^11.0.0 || ^12.0.0 || ^13.0.0 || ^14.0.0",
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0"
+      }
+    },
+    "node_modules/next-intl/node_modules/@formatjs/intl-localematcher": {
+      "version": "0.2.32",
+      "resolved": "https://registry.npmjs.org/@formatjs/intl-localematcher/-/intl-localematcher-0.2.32.tgz",
+      "integrity": "sha512-k/MEBstff4sttohyEpXxCmC3MqbUn9VvHGlZ8fauLzkbwXmVrEeyzS+4uhrvAk9DWU9/7otYWxyDox4nT/KVLQ==",
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
     "node_modules/next-s3-upload": {
       "version": "0.3.4",
       "resolved": "https://registry.npmjs.org/next-s3-upload/-/next-s3-upload-0.3.4.tgz",
@@ -8674,6 +8775,18 @@
         }
       }
     },
+    "node_modules/use-intl": {
+      "version": "3.17.2",
+      "resolved": "https://registry.npmjs.org/use-intl/-/use-intl-3.17.2.tgz",
+      "integrity": "sha512-9lPgt41nS8x4AYCLfIC9VKCmamnVxzPM2nze7lpp/I1uaSSQvIz5MQpYUFikv08cMUsCwAWahU0e+arHInpdcw==",
+      "dependencies": {
+        "@formatjs/fast-memoize": "^2.2.0",
+        "intl-messageformat": "^10.5.14"
+      },
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0"
+      }
+    },
     "node_modules/use-sidecar": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/use-sidecar/-/use-sidecar-1.1.2.tgz",

package.json

@@ -15,6 +15,7 @@
     "start-container": "docker compose --env-file container.env up"
   },
   "dependencies": {
+    "@formatjs/intl-localematcher": "^0.5.4",
     "@hookform/resolvers": "^3.3.2",
     "@prisma/client": "^5.6.0",
     "@radix-ui/react-checkbox": "^1.0.4",
@@ -39,7 +40,9 @@
     "embla-carousel-react": "^8.0.0-rc21",
     "lucide-react": "^0.290.0",
     "nanoid": "^5.0.4",
+    "negotiator": "^0.6.3",
     "next": "^14.2.3",
+    "next-intl": "^3.17.2",
     "next-s3-upload": "^0.3.4",
     "next-themes": "^0.2.1",
     "next13-progressbar": "^1.1.1",
@@ -61,6 +64,7 @@
   "devDependencies": {
     "@total-typescript/ts-reset": "^0.5.1",
     "@types/content-disposition": "^0.5.8",
+    "@types/negotiator": "^0.6.3",
     "@types/node": "^20",
     "@types/pg": "^8.10.9",
     "@types/react": "^18.2.48",

src/app/groups/[groupId]/activity/activity-item.tsx

@@ -4,6 +4,7 @@ import { getGroupExpenses } from '@/lib/api'
 import { DateTimeStyle, cn, formatDate } from '@/lib/utils'
 import { Activity, ActivityType, Participant } from '@prisma/client'
 import { ChevronRight } from 'lucide-react'
+import { useLocale, useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 
@@ -15,36 +16,27 @@ type Props = {
   dateStyle: DateTimeStyle
 }
 
-function getSummary(activity: Activity, participantName?: string) {
+function useSummary(activity: Activity, participantName?: string) {
-  const participant = participantName ?? 'Someone'
+  const t = useTranslations('Activity')
+  const participant = participantName ?? t('someone')
   const expense = activity.data ?? ''
+
+  const tr = (key: string) =>
+    t.rich(key, {
+      expense,
+      participant,
+      em: (chunks) => <em>&ldquo;{chunks}&rdquo;</em>,
+      strong: (chunks) => <strong>{chunks}</strong>,
+    })
+
   if (activity.activityType == ActivityType.UPDATE_GROUP) {
-    return (
+    return <>{tr('settingsModified')}</>
-      <>
-        Group settings were modified by <strong>{participant}</strong>
-      </>
-    )
   } else if (activity.activityType == ActivityType.CREATE_EXPENSE) {
-    return (
+    return <>{tr('expenseCreated')}</>
-      <>
-        Expense <em>&ldquo;{expense}&rdquo;</em> created by{' '}
-        <strong>{participant}</strong>.
-      </>
-    )
   } else if (activity.activityType == ActivityType.UPDATE_EXPENSE) {
-    return (
+    return <>{tr('expenseUpdated')}</>
-      <>
-        Expense <em>&ldquo;{expense}&rdquo;</em> updated by{' '}
-        <strong>{participant}</strong>.
-      </>
-    )
   } else if (activity.activityType == ActivityType.DELETE_EXPENSE) {
-    return (
+    return <>{tr('expenseDeleted')}</>
-      <>
-        Expense <em>&ldquo;{expense}&rdquo;</em> deleted by{' '}
-        <strong>{participant}</strong>.
-      </>
-    )
   }
 }
 
@@ -56,9 +48,10 @@ export function ActivityItem({
   dateStyle,
 }: Props) {
   const router = useRouter()
+  const locale = useLocale()
 
   const expenseExists = expense !== undefined
-  const summary = getSummary(activity, participant?.name)
+  const summary = useSummary(activity, participant?.name)
 
   return (
     <div
@@ -75,11 +68,11 @@ export function ActivityItem({
       <div className="flex flex-col justify-between items-start">
         {dateStyle !== undefined && (
           <div className="mt-1 text-xs/5 text-muted-foreground">
-            {formatDate(activity.time, { dateStyle })}
+            {formatDate(activity.time, locale, { dateStyle })}
           </div>
         )}
         <div className="my-1 text-xs/5 text-muted-foreground">
-          {formatDate(activity.time, { timeStyle: 'short' })}
+          {formatDate(activity.time, locale, { timeStyle: 'short' })}
         </div>
       </div>
       <div className="flex-1">

src/app/groups/[groupId]/activity/activity-list.tsx

@@ -2,6 +2,7 @@ import { ActivityItem } from '@/app/groups/[groupId]/activity/activity-item'
 import { getGroupExpenses } from '@/lib/api'
 import { Activity, Participant } from '@prisma/client'
 import dayjs, { type Dayjs } from 'dayjs'
+import { useTranslations } from 'next-intl'
 
 type Props = {
   groupId: string
@@ -11,15 +12,15 @@ type Props = {
 }
 
 const DATE_GROUPS = {
-  TODAY: 'Today',
+  TODAY: 'today',
-  YESTERDAY: 'Yesterday',
+  YESTERDAY: 'yesterday',
-  EARLIER_THIS_WEEK: 'Earlier this week',
+  EARLIER_THIS_WEEK: 'earlierThisWeek',
-  LAST_WEEK: 'Last week',
+  LAST_WEEK: 'lastWeek',
-  EARLIER_THIS_MONTH: 'Earlier this month',
+  EARLIER_THIS_MONTH: 'earlierThisMonth',
-  LAST_MONTH: 'Last month',
+  LAST_MONTH: 'lastMonth',
-  EARLIER_THIS_YEAR: 'Earlier this year',
+  EARLIER_THIS_YEAR: 'earlierThisYear',
-  LAST_YEAR: 'Last year',
+  LAST_YEAR: 'lastYear',
-  OLDER: 'Older',
+  OLDER: 'older',
 }
 
 function getDateGroup(date: Dayjs, today: Dayjs) {
@@ -63,6 +64,7 @@ export function ActivityList({
   expenses,
   activities,
 }: Props) {
+  const t = useTranslations('Activity')
   const groupedActivitiesByDate = getGroupedActivitiesByDate(activities)
 
   return activities.length > 0 ? (
@@ -82,7 +84,7 @@ export function ActivityList({
                 'text-muted-foreground text-xs py-1 font-semibold sticky top-16 bg-white dark:bg-[#1b1917]'
               }
             >
-              {dateGroup}
+              {t(`Groups.${dateGroup}`)}
             </div>
             {groupActivities.map((activity: Activity) => {
               const participant =
@@ -105,8 +107,6 @@ export function ActivityList({
       })}
     </>
   ) : (
-    <p className="px-6 text-sm py-6">
+    <p className="px-6 text-sm py-6">{t('noActivity')}</p>
-      There is not yet any activity in your group.
-    </p>
   )
 }

src/app/groups/[groupId]/activity/page.tsx

@@ -9,6 +9,7 @@ import {
 } from '@/components/ui/card'
 import { getActivities, getGroupExpenses } from '@/lib/api'
 import { Metadata } from 'next'
+import { getTranslations } from 'next-intl/server'
 import { notFound } from 'next/navigation'
 
 export const metadata: Metadata = {
@@ -20,6 +21,7 @@ export default async function ActivityPage({
 }: {
   params: { groupId: string }
 }) {
+  const t = await getTranslations('Activity')
   const group = await cached.getGroup(groupId)
   if (!group) notFound()
 
@@ -30,10 +32,8 @@ export default async function ActivityPage({
     <>
       <Card className="mb-4">
         <CardHeader>
-          <CardTitle>Activity</CardTitle>
+          <CardTitle>{t('title')}</CardTitle>
-          <CardDescription>
+          <CardDescription>{t('description')}</CardDescription>
-            Overview of all activity in this group.
-          </CardDescription>
         </CardHeader>
         <CardContent className="flex flex-col space-y-4">
           <ActivityList

src/app/groups/[groupId]/balances-list.tsx

@@ -1,6 +1,7 @@
 import { Balances } from '@/lib/balances'
 import { cn, formatCurrency } from '@/lib/utils'
 import { Participant } from '@prisma/client'
+import { useLocale } from 'next-intl'
 
 type Props = {
   balances: Balances
@@ -9,6 +10,7 @@ type Props = {
 }
 
 export function BalancesList({ balances, participants, currency }: Props) {
+  const locale = useLocale()
   const maxBalance = Math.max(
     ...Object.values(balances).map((b) => Math.abs(b.total)),
   )
@@ -28,7 +30,7 @@ export function BalancesList({ balances, participants, currency }: Props) {
             </div>
             <div className={cn('w-1/2 relative', isLeft || 'text-right')}>
               <div className="absolute inset-0 p-2 z-20">
-                {formatCurrency(currency, balance)}
+                {formatCurrency(currency, balance, locale)}
               </div>
               {balance !== 0 && (
                 <div

src/app/groups/[groupId]/balances/page.tsx

@@ -15,6 +15,7 @@ import {
   getSuggestedReimbursements,
 } from '@/lib/balances'
 import { Metadata } from 'next'
+import { getTranslations } from 'next-intl/server'
 import { notFound } from 'next/navigation'
 
 export const metadata: Metadata = {
@@ -26,6 +27,7 @@ export default async function GroupPage({
 }: {
   params: { groupId: string }
 }) {
+  const t = await getTranslations('Balances')
   const group = await cached.getGroup(groupId)
   if (!group) notFound()
 
@@ -38,10 +40,8 @@ export default async function GroupPage({
     <>
       <Card className="mb-4">
         <CardHeader>
-          <CardTitle>Balances</CardTitle>
+          <CardTitle>{t('title')}</CardTitle>
-          <CardDescription>
+          <CardDescription>{t('description')}</CardDescription>
-            This is the amount that each participant paid or was paid for.
-          </CardDescription>
         </CardHeader>
         <CardContent>
           <BalancesList
@@ -53,11 +53,8 @@ export default async function GroupPage({
       </Card>
       <Card className="mb-4">
         <CardHeader>
-          <CardTitle>Suggested reimbursements</CardTitle>
+          <CardTitle>{t('Reimbursements.title')}</CardTitle>
-          <CardDescription>
+          <CardDescription>{t('Reimbursements.description')}</CardDescription>
-            Here are suggestions for optimized reimbursements between
-            participants.
-          </CardDescription>
         </CardHeader>
         <CardContent className="p-0">
           <ReimbursementList

src/app/groups/[groupId]/expenses/active-user-balance.tsx

@@ -2,6 +2,7 @@
 import { Money } from '@/components/money'
 import { getBalances } from '@/lib/balances'
 import { useActiveUser } from '@/lib/hooks'
+import { useTranslations } from 'next-intl'
 
 type Props = {
   groupId: string
@@ -10,6 +11,7 @@ type Props = {
 }
 
 export function ActiveUserBalance({ groupId, currency, expense }: Props) {
+  const t = useTranslations('ExpenseCard')
   const activeUserId = useActiveUser(groupId)
   if (activeUserId === null || activeUserId === '' || activeUserId === 'None') {
     return null
@@ -33,7 +35,7 @@ export function ActiveUserBalance({ groupId, currency, expense }: Props) {
     }
     fmtBalance = (
       <>
-        Your balance:{' '}
+        {t('yourBalance')}{' '}
         <Money {...{ currency, amount: balance.total }} bold colored />
         {balanceDetail}
       </>

src/app/groups/[groupId]/expenses/active-user-modal.tsx

@@ -12,7 +12,6 @@ import {
 import {
   Drawer,
   DrawerContent,
-  DrawerDescription,
   DrawerFooter,
   DrawerHeader,
   DrawerTitle,
@@ -22,6 +21,7 @@ import { RadioGroup, RadioGroupItem } from '@/components/ui/radio-group'
 import { getGroup } from '@/lib/api'
 import { useMediaQuery } from '@/lib/hooks'
 import { cn } from '@/lib/utils'
+import { useTranslations } from 'next-intl'
 import { ComponentProps, useEffect, useState } from 'react'
 
 type Props = {
@@ -29,6 +29,7 @@ type Props = {
 }
 
 export function ActiveUserModal({ group }: Props) {
+  const t = useTranslations('Expenses.ActiveUserModal')
   const [open, setOpen] = useState(false)
   const isDesktop = useMediaQuery('(min-width: 768px)')
 
@@ -52,16 +53,13 @@ export function ActiveUserModal({ group }: Props) {
       <Dialog open={open} onOpenChange={updateOpen}>
         <DialogContent className="sm:max-w-[425px]">
           <DialogHeader>
-            <DialogTitle>Who are you?</DialogTitle>
+            <DialogTitle>{t('title')}</DialogTitle>
-            <DialogDescription>
+            <DialogDescription>{t('description')}</DialogDescription>
-              Tell us which participant you are to let us customize how the
-              information is displayed.
-            </DialogDescription>
           </DialogHeader>
           <ActiveUserForm group={group} close={() => setOpen(false)} />
           <DialogFooter className="sm:justify-center">
             <p className="text-sm text-center text-muted-foreground">
-              This setting can be changed later in the group settings.
+              {t('footer')}
             </p>
           </DialogFooter>
         </DialogContent>
@@ -73,11 +71,8 @@ export function ActiveUserModal({ group }: Props) {
     <Drawer open={open} onOpenChange={updateOpen}>
       <DrawerContent>
         <DrawerHeader className="text-left">
-          <DrawerTitle>Who are you?</DrawerTitle>
+          <DrawerTitle>{t('title')}</DrawerTitle>
-          <DrawerDescription>
+          <DialogDescription>{t('description')}</DialogDescription>
-            Tell us which participant you are to let us customize how the
-            information is displayed.
-          </DrawerDescription>
         </DrawerHeader>
         <ActiveUserForm
           className="px-4"
@@ -86,7 +81,7 @@ export function ActiveUserModal({ group }: Props) {
         />
         <DrawerFooter className="pt-2">
           <p className="text-sm text-center text-muted-foreground">
-            This setting can be changed later in the group settings.
+            {t('footer')}
           </p>
         </DrawerFooter>
       </DrawerContent>
@@ -99,6 +94,7 @@ function ActiveUserForm({
   close,
   className,
 }: ComponentProps<'form'> & { group: Props['group']; close: () => void }) {
+  const t = useTranslations('Expenses.ActiveUserModal')
   const [selected, setSelected] = useState('None')
 
   return (
@@ -115,7 +111,7 @@ function ActiveUserForm({
           <div className="flex items-center space-x-2">
             <RadioGroupItem value="none" id="none" />
             <Label htmlFor="none" className="italic font-normal flex-1">
-              I don’t want to select anyone
+              {t('nobody')}
             </Label>
           </div>
           {group.participants.map((participant) => (
@@ -128,7 +124,7 @@ function ActiveUserForm({
           ))}
         </div>
       </RadioGroup>
-      <Button type="submit">Save changes</Button>
+      <Button type="submit">{t('save')}</Button>
     </form>
   )
 }

src/app/groups/[groupId]/expenses/create-from-receipt-button.tsx

@@ -29,6 +29,7 @@ import { useMediaQuery } from '@/lib/hooks'
 import { formatCurrency, formatDate, formatFileSize } from '@/lib/utils'
 import { Category } from '@prisma/client'
 import { ChevronRight, FileQuestion, Loader2, Receipt } from 'lucide-react'
+import { useLocale, useTranslations } from 'next-intl'
 import { getImageData, usePresignedUpload } from 'next-s3-upload'
 import Image from 'next/image'
 import { useRouter } from 'next/navigation'
@@ -47,6 +48,8 @@ export function CreateFromReceiptButton({
   groupCurrency,
   categories,
 }: Props) {
+  const locale = useLocale()
+  const t = useTranslations('CreateFromReceipt')
   const [pending, setPending] = useState(false)
   const { uploadToS3, FileInput, openFileDialog } = usePresignedUpload()
   const { toast } = useToast()
@@ -60,10 +63,11 @@ export function CreateFromReceiptButton({
   const handleFileChange = async (file: File) => {
     if (file.size > MAX_FILE_SIZE) {
       toast({
-        title: 'The file is too big',
+        title: t('TooBigToast.title'),
-        description: `The maximum file size you can upload is ${formatFileSize(
+        description: t('TooBigToast.description', {
-          MAX_FILE_SIZE,
+          maxSize: formatFileSize(MAX_FILE_SIZE, locale),
-        )}. Yours is ${formatFileSize(file.size)}.`,
+          size: formatFileSize(file.size, locale),
+        }),
         variant: 'destructive',
       })
       return
@@ -82,13 +86,15 @@ export function CreateFromReceiptButton({
       } catch (err) {
         console.error(err)
         toast({
-          title: 'Error while uploading document',
+          title: t('ErrorToast.title'),
-          description:
+          description: t('ErrorToast.description'),
-            'Something wrong happened when uploading the document. Please retry later or select a different file.',
           variant: 'destructive',
           action: (
-            <ToastAction altText="Retry" onClick={() => upload()}>
+            <ToastAction
-              Retry
+              altText={t('ErrorToast.retry')}
+              onClick={() => upload()}
+            >
+              {t('ErrorToast.retry')}
             </ToastAction>
           ),
         })
@@ -114,26 +120,23 @@ export function CreateFromReceiptButton({
         <Button
           size="icon"
           variant="secondary"
-          title="Create expense from receipt"
+          title={t('Dialog.triggerTitle')}
         >
           <Receipt className="w-4 h-4" />
         </Button>
       }
       title={
         <>
-          <span>Create from receipt</span>
+          <span>{t('Dialog.title')}</span>
           <Badge className="bg-pink-700 hover:bg-pink-600 dark:bg-pink-500 dark:hover:bg-pink-600">
             Beta
           </Badge>
         </>
       }
-      description={<>Extract the expense information from a receipt photo.</>}
+      description={<>{t('Dialog.description')}</>}
     >
       <div className="prose prose-sm dark:prose-invert">
-        <p>
+        <p>{t('Dialog.body')}</p>
-          Upload the photo of a receipt, and we’ll scan it to extract the
-          expense information if we can.
-        </p>
         <div>
           <FileInput
             onChange={handleFileChange}
@@ -161,16 +164,16 @@ export function CreateFromReceiptButton({
                 </div>
               ) : (
                 <span className="text-xs sm:text-sm text-muted-foreground">
-                  Select image…
+                  {t('Dialog.selectImage')}
                 </span>
               )}
             </Button>
             <div className="col-span-2">
-              <strong>Title:</strong>
+              <strong>{t('Dialog.titleLabel')}</strong>
               <div>{receiptInfo ? receiptInfo.title ?? <Unknown /> : '…'}</div>
             </div>
             <div className="col-span-2">
-              <strong>Category:</strong>
+              <strong>{t('Dialog.categoryLabel')}</strong>
               <div>
                 {receiptInfo ? (
                   receiptInfoCategory ? (
@@ -194,11 +197,17 @@ export function CreateFromReceiptButton({
               </div>
             </div>
             <div>
-              <strong>Amount:</strong>
+              <strong>{t('Dialog.amountLabel')}</strong>
               <div>
                 {receiptInfo ? (
                   receiptInfo.amount ? (
-                    <>{formatCurrency(groupCurrency, receiptInfo.amount)}</>
+                    <>
+                      {formatCurrency(
+                        groupCurrency,
+                        receiptInfo.amount,
+                        locale,
+                      )}
+                    </>
                   ) : (
                     <Unknown />
                   )
@@ -208,13 +217,15 @@ export function CreateFromReceiptButton({
               </div>
             </div>
             <div>
-              <strong>Date:</strong>
+              <strong>{t('Dialog.dateLabel')}</strong>
               <div>
                 {receiptInfo ? (
                   receiptInfo.date ? (
-                    formatDate(new Date(`${receiptInfo?.date}T12:00:00.000Z`), {
+                    formatDate(
-                      dateStyle: 'medium',
+                      new Date(`${receiptInfo?.date}T12:00:00.000Z`),
-                    })
+                      locale,
+                      { dateStyle: 'medium' },
+                    )
                   ) : (
                     <Unknown />
                   )
@@ -225,7 +236,7 @@ export function CreateFromReceiptButton({
             </div>
           </div>
         </div>
-        <p>You’ll be able to edit the expense information next.</p>
+        <p>{t('Dialog.editNext')}</p>
         <div className="text-center">
           <Button
             disabled={pending || !receiptInfo}
@@ -244,7 +255,7 @@ export function CreateFromReceiptButton({
               )
             }}
           >
-            Continue
+            {t('Dialog.continue')}
           </Button>
         </div>
       </div>
@@ -253,10 +264,11 @@ export function CreateFromReceiptButton({
 }
 
 function Unknown() {
+  const t = useTranslations('CreateFromReceipt')
   return (
     <div className="flex gap-1 items-center text-muted-foreground">
       <FileQuestion className="w-4 h-4" />
-      <em>Unknown</em>
+      <em>{t('unknown')}</em>
     </div>
   )
 }

src/app/groups/[groupId]/expenses/expense-card.tsx

@@ -5,18 +5,40 @@ import { Button } from '@/components/ui/button'
 import { getGroupExpenses } from '@/lib/api'
 import { cn, formatCurrency, formatDate } from '@/lib/utils'
 import { ChevronRight } from 'lucide-react'
+import { useLocale, useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 import { Fragment } from 'react'
 
+type Expense = Awaited<ReturnType<typeof getGroupExpenses>>[number]
+
+function Participants({ expense }: { expense: Expense }) {
+  const t = useTranslations('ExpenseCard')
+  const key = expense.amount > 0 ? 'paidBy' : 'receivedBy'
+  const paidFor = expense.paidFor.map((paidFor, index) => (
+    <Fragment key={index}>
+      {index !== 0 && <>, </>}
+      <strong>{paidFor.participant.name}</strong>
+    </Fragment>
+  ))
+  const participants = t.rich(key, {
+    strong: (chunks) => <strong>{chunks}</strong>,
+    paidBy: expense.paidBy.name,
+    paidFor: () => paidFor,
+    forCount: expense.paidFor.length,
+  })
+  return <>{participants}</>
+}
+
 type Props = {
-  expense: Awaited<ReturnType<typeof getGroupExpenses>>[number]
+  expense: Expense
   currency: string
   groupId: string
 }
 
 export function ExpenseCard({ expense, currency, groupId }: Props) {
   const router = useRouter()
+  const locale = useLocale()
 
   return (
     <div
@@ -38,14 +60,7 @@ export function ExpenseCard({ expense, currency, groupId }: Props) {
           {expense.title}
         </div>
         <div className="text-xs text-muted-foreground">
-          {expense.amount > 0 ? 'Paid by ' : 'Received by '}
+          <Participants expense={expense} />
-          <strong>{expense.paidBy.name}</strong> for{' '}
-          {expense.paidFor.map((paidFor, index) => (
-            <Fragment key={index}>
-              {index !== 0 && <>, </>}
-              <strong>{paidFor.participant.name}</strong>
-            </Fragment>
-          ))}
         </div>
         <div className="text-xs text-muted-foreground">
           <ActiveUserBalance {...{ groupId, currency, expense }} />
@@ -58,10 +73,10 @@ export function ExpenseCard({ expense, currency, groupId }: Props) {
             expense.isReimbursement ? 'italic' : 'font-bold',
           )}
         >
-          {formatCurrency(currency, expense.amount)}
+          {formatCurrency(currency, expense.amount, locale)}
         </div>
         <div className="text-xs text-muted-foreground">
-          {formatDate(expense.expenseDate, { dateStyle: 'medium' })}
+          {formatDate(expense.expenseDate, locale, { dateStyle: 'medium' })}
         </div>
       </div>
       <Button

src/app/groups/[groupId]/expenses/expense-list.tsx

@@ -7,6 +7,7 @@ import { Skeleton } from '@/components/ui/skeleton'
 import { normalizeString } from '@/lib/utils'
 import { Participant } from '@prisma/client'
 import dayjs, { type Dayjs } from 'dayjs'
+import { useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useEffect, useMemo, useState } from 'react'
 import { useInView } from 'react-intersection-observer'
@@ -24,13 +25,13 @@ type Props = {
 }
 
 const EXPENSE_GROUPS = {
-  UPCOMING: 'Upcoming',
+  UPCOMING: 'upcoming',
-  THIS_WEEK: 'This week',
+  THIS_WEEK: 'thisWeek',
-  EARLIER_THIS_MONTH: 'Earlier this month',
+  EARLIER_THIS_MONTH: 'earlierThisMonth',
-  LAST_MONTH: 'Last month',
+  LAST_MONTH: 'lastMonth',
-  EARLIER_THIS_YEAR: 'Earlier this year',
+  EARLIER_THIS_YEAR: 'earlierThisYear',
-  LAST_YEAR: 'Last year',
+  LAST_YEAR: 'lastYear',
-  OLDER: 'Older',
+  OLDER: 'older',
 }
 
 function getExpenseGroup(date: Dayjs, today: Dayjs) {
@@ -76,6 +77,7 @@ export function ExpenseList({
   const [isFetching, setIsFetching] = useState(false)
   const [expenses, setExpenses] = useState(expensesFirstPage)
   const { ref, inView } = useInView()
+  const t = useTranslations('Expenses')
 
   useEffect(() => {
     const activeUser = localStorage.getItem('newGroup-activeUser')
@@ -155,7 +157,7 @@ export function ExpenseList({
                 'text-muted-foreground text-xs pl-4 sm:pl-6 py-1 font-semibold sticky top-16 bg-white dark:bg-[#1b1917]'
               }
             >
-              {expenseGroup}
+              {t(`Groups.${expenseGroup}`)}
             </div>
             {groupExpenses.map((expense) => (
               <ExpenseCard
@@ -187,10 +189,10 @@ export function ExpenseList({
     </>
   ) : (
     <p className="px-6 text-sm py-6">
-      Your group doesn’t contain any expense yet.{' '}
+      {t('noExpenses')}{' '}
       <Button variant="link" asChild className="-m-4">
         <Link href={`/groups/${groupId}/expenses/create`}>
-          Create the first one
+          {t('createFirst')}
         </Link>
       </Button>
     </p>

src/app/groups/[groupId]/expenses/page.tsx

@@ -19,6 +19,7 @@ import {
 import { env } from '@/lib/env'
 import { Download, Plus } from 'lucide-react'
 import { Metadata } from 'next'
+import { getTranslations } from 'next-intl/server'
 import Link from 'next/link'
 import { notFound } from 'next/navigation'
 import { Suspense } from 'react'
@@ -34,6 +35,7 @@ export default async function GroupExpensesPage({
 }: {
   params: { groupId: string }
 }) {
+  const t = await getTranslations('Expenses')
   const group = await cached.getGroup(groupId)
   if (!group) notFound()
 
@@ -44,10 +46,8 @@ export default async function GroupExpensesPage({
       <Card className="mb-4 rounded-none -mx-4 border-x-0 sm:border-x sm:rounded-lg sm:mx-0">
         <div className="flex flex-1">
           <CardHeader className="flex-1 p-4 sm:p-6">
-            <CardTitle>Expenses</CardTitle>
+            <CardTitle>{t('title')}</CardTitle>
-            <CardDescription>
+            <CardDescription>{t('description')}</CardDescription>
-              Here are the expenses that you created for your group.
-            </CardDescription>
           </CardHeader>
           <CardHeader className="p-4 sm:p-6 flex flex-row space-y-0 gap-2">
             <Button variant="secondary" size="icon" asChild>
@@ -55,7 +55,7 @@ export default async function GroupExpensesPage({
                 prefetch={false}
                 href={`/groups/${groupId}/expenses/export/json`}
                 target="_blank"
-                title="Export to JSON"
+                title={t('exportJson')}
               >
                 <Download className="w-4 h-4" />
               </Link>
@@ -70,7 +70,7 @@ export default async function GroupExpensesPage({
             <Button asChild size="icon">
               <Link
                 href={`/groups/${groupId}/expenses/create`}
-                title="Create expense"
+                title={t('create')}
               >
                 <Plus className="w-4 h-4" />
               </Link>

src/app/groups/[groupId]/group-tabs.tsx

@@ -1,5 +1,6 @@
 'use client'
 import { Tabs, TabsList, TabsTrigger } from '@/components/ui/tabs'
+import { useTranslations } from 'next-intl'
 import { usePathname, useRouter } from 'next/navigation'
 
 type Props = {
@@ -7,6 +8,7 @@ type Props = {
 }
 
 export function GroupTabs({ groupId }: Props) {
+  const t = useTranslations()
   const pathname = usePathname()
   const value =
     pathname.replace(/\/groups\/[^\/]+\/([^/]+).*/, '$1') || 'expenses'
@@ -21,11 +23,11 @@ export function GroupTabs({ groupId }: Props) {
       }}
     >
       <TabsList>
-        <TabsTrigger value="expenses">Expenses</TabsTrigger>
+        <TabsTrigger value="expenses">{t('Expenses.title')}</TabsTrigger>
-        <TabsTrigger value="balances">Balances</TabsTrigger>
+        <TabsTrigger value="balances">{t('Balances.title')}</TabsTrigger>
-        <TabsTrigger value="stats">Stats</TabsTrigger>
+        <TabsTrigger value="stats">{t('Stats.title')}</TabsTrigger>
-        <TabsTrigger value="activity">Activity</TabsTrigger>
+        <TabsTrigger value="activity">{t('Activity.title')}</TabsTrigger>
-        <TabsTrigger value="edit">Settings</TabsTrigger>
+        <TabsTrigger value="edit">{t('Settings.title')}</TabsTrigger>
       </TabsList>
     </Tabs>
   )

src/app/groups/[groupId]/reimbursement-list.tsx

@@ -2,6 +2,7 @@ import { Button } from '@/components/ui/button'
 import { Reimbursement } from '@/lib/balances'
 import { formatCurrency } from '@/lib/utils'
 import { Participant } from '@prisma/client'
+import { useLocale, useTranslations } from 'next-intl'
 import Link from 'next/link'
 
 type Props = {
@@ -17,12 +18,10 @@ export function ReimbursementList({
   currency,
   groupId,
 }: Props) {
+  const locale = useLocale()
+  const t = useTranslations('Balances.Reimbursements')
   if (reimbursements.length === 0) {
-    return (
+    return <p className="px-6 text-sm pb-6">{t('noImbursements')}</p>
-      <p className="px-6 text-sm pb-6">
-        It looks like your group doesn’t need any reimbursement 😁
-      </p>
-    )
   }
 
   const getParticipant = (id: string) => participants.find((p) => p.id === id)
@@ -32,18 +31,21 @@ export function ReimbursementList({
         <div className="border-t px-6 py-4 flex justify-between" key={index}>
           <div className="flex flex-col gap-1 items-start sm:flex-row sm:items-baseline sm:gap-4">
             <div>
-              <strong>{getParticipant(reimbursement.from)?.name}</strong> owes{' '}
+              {t.rich('owes', {
-              <strong>{getParticipant(reimbursement.to)?.name}</strong>
+                from: getParticipant(reimbursement.from)?.name,
+                to: getParticipant(reimbursement.to)?.name,
+                strong: (chunks) => <strong>{chunks}</strong>,
+              })}
             </div>
             <Button variant="link" asChild className="-mx-4 -my-3">
               <Link
                 href={`/groups/${groupId}/expenses/create?reimbursement=yes&from=${reimbursement.from}&to=${reimbursement.to}&amount=${reimbursement.amount}`}
               >
-                Mark as paid
+                {t('markAsPaid')}
               </Link>
             </Button>
           </div>
-          <div>{formatCurrency(currency, reimbursement.amount)}</div>
+          <div>{formatCurrency(currency, reimbursement.amount, locale)}</div>
         </div>
       ))}
     </div>

src/app/groups/[groupId]/share-button.tsx

@@ -11,27 +11,26 @@ import {
 import { useBaseUrl } from '@/lib/hooks'
 import { Group } from '@prisma/client'
 import { Share } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 
 type Props = {
   group: Group
 }
 
 export function ShareButton({ group }: Props) {
+  const t = useTranslations('Share')
   const baseUrl = useBaseUrl()
   const url = baseUrl && `${baseUrl}/groups/${group.id}/expenses?ref=share`
 
   return (
     <Popover>
       <PopoverTrigger asChild>
-        <Button title="Share" size="icon" className="flex-shrink-0">
+        <Button title={t('title')} size="icon" className="flex-shrink-0">
           <Share className="w-4 h-4" />
         </Button>
       </PopoverTrigger>
       <PopoverContent align="end" className="[&_p]:text-sm flex flex-col gap-3">
-        <p>
+        <p>{t('description')}</p>
-          For other participants to see the group and add expenses, share its
-          URL with them.
-        </p>
         {url && (
           <div className="flex gap-2">
             <Input className="flex-1" defaultValue={url} readOnly />
@@ -43,8 +42,7 @@ export function ShareButton({ group }: Props) {
           </div>
         )}
         <p>
-          <strong>Warning!</strong> Every person with the group URL will be able
+          <strong>{t('warning')}</strong> {t('warningHelp')}
-          to see and edit expenses. Share with caution!
         </p>
       </PopoverContent>
     </Popover>

src/app/groups/[groupId]/stats/page.tsx

@@ -10,6 +10,7 @@ import {
 import { getGroupExpenses } from '@/lib/api'
 import { getTotalGroupSpending } from '@/lib/totals'
 import { Metadata } from 'next'
+import { getTranslations } from 'next-intl/server'
 import { notFound } from 'next/navigation'
 
 export const metadata: Metadata = {
@@ -21,6 +22,7 @@ export default async function TotalsPage({
 }: {
   params: { groupId: string }
 }) {
+  const t = await getTranslations('Stats')
   const group = await cached.getGroup(groupId)
   if (!group) notFound()
 
@@ -31,10 +33,8 @@ export default async function TotalsPage({
     <>
       <Card className="mb-4">
         <CardHeader>
-          <CardTitle>Totals</CardTitle>
+          <CardTitle>{t('Totals.title')}</CardTitle>
-          <CardDescription>
+          <CardDescription>{t('Totals.description')}</CardDescription>
-            Spending summary of the entire group.
-          </CardDescription>
         </CardHeader>
         <CardContent className="flex flex-col space-y-4">
           <Totals

src/app/groups/[groupId]/stats/totals-group-spending.tsx

@@ -1,4 +1,5 @@
 import { formatCurrency } from '@/lib/utils'
+import { useLocale, useTranslations } from 'next-intl'
 
 type Props = {
   totalGroupSpendings: number
@@ -6,12 +7,14 @@ type Props = {
 }
 
 export function TotalsGroupSpending({ totalGroupSpendings, currency }: Props) {
-  const balance = totalGroupSpendings < 0 ? 'earnings' : 'spendings'
+  const locale = useLocale()
+  const t = useTranslations('Stats.Totals')
+  const balance = totalGroupSpendings < 0 ? 'groupEarnings' : 'groupSpendings'
   return (
     <div>
-      <div className="text-muted-foreground">Total group {balance}</div>
+      <div className="text-muted-foreground">{t(balance)}</div>
       <div className="text-lg">
-        {formatCurrency(currency, Math.abs(totalGroupSpendings))}
+        {formatCurrency(currency, Math.abs(totalGroupSpendings), locale)}
       </div>
     </div>
   )

src/app/groups/[groupId]/stats/totals-your-share.tsx

@@ -2,6 +2,7 @@
 import { getGroup, getGroupExpenses } from '@/lib/api'
 import { getTotalActiveUserShare } from '@/lib/totals'
 import { cn, formatCurrency } from '@/lib/utils'
+import { useLocale, useTranslations } from 'next-intl'
 import { useEffect, useState } from 'react'
 
 type Props = {
@@ -10,6 +11,8 @@ type Props = {
 }
 
 export function TotalsYourShare({ group, expenses }: Props) {
+  const locale = useLocale()
+  const t = useTranslations('Stats.Totals')
   const [activeUser, setActiveUser] = useState('')
 
   useEffect(() => {
@@ -25,14 +28,14 @@ export function TotalsYourShare({ group, expenses }: Props) {
 
   return (
     <div>
-      <div className="text-muted-foreground">Your total share</div>
+      <div className="text-muted-foreground">{t('yourShare')}</div>
       <div
         className={cn(
           'text-lg',
           totalActiveUserShare < 0 ? 'text-green-600' : 'text-red-600',
         )}
       >
-        {formatCurrency(currency, Math.abs(totalActiveUserShare))}
+        {formatCurrency(currency, Math.abs(totalActiveUserShare), locale)}
       </div>
     </div>
   )

src/app/groups/[groupId]/stats/totals-your-spending.tsx

@@ -3,6 +3,7 @@ import { getGroup, getGroupExpenses } from '@/lib/api'
 import { useActiveUser } from '@/lib/hooks'
 import { getTotalActiveUserPaidFor } from '@/lib/totals'
 import { cn, formatCurrency } from '@/lib/utils'
+import { useLocale, useTranslations } from 'next-intl'
 
 type Props = {
   group: NonNullable<Awaited<ReturnType<typeof getGroup>>>
@@ -10,6 +11,8 @@ type Props = {
 }
 
 export function TotalsYourSpendings({ group, expenses }: Props) {
+  const locale = useLocale()
+  const t = useTranslations('Stats.Totals')
   const activeUser = useActiveUser(group.id)
 
   const totalYourSpendings =
@@ -17,11 +20,11 @@ export function TotalsYourSpendings({ group, expenses }: Props) {
       ? 0
       : getTotalActiveUserPaidFor(activeUser, expenses)
   const currency = group.currency
-  const balance = totalYourSpendings < 0 ? 'earnings' : 'spendings'
+  const balance = totalYourSpendings < 0 ? 'yourEarnings' : 'yourSpendings'
 
   return (
     <div>
-      <div className="text-muted-foreground">Your total {balance}</div>
+      <div className="text-muted-foreground">{t(balance)}</div>
 
       <div
         className={cn(
@@ -29,7 +32,7 @@ export function TotalsYourSpendings({ group, expenses }: Props) {
           totalYourSpendings < 0 ? 'text-green-600' : 'text-red-600',
         )}
       >
-        {formatCurrency(currency, Math.abs(totalYourSpendings))}
+        {formatCurrency(currency, Math.abs(totalYourSpendings), locale)}
       </div>
     </div>
   )

src/app/groups/add-group-by-url-button.tsx

@@ -9,6 +9,7 @@ import {
 } from '@/components/ui/popover'
 import { useMediaQuery } from '@/lib/hooks'
 import { Loader2, Plus } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 import { useState } from 'react'
 
 type Props = {
@@ -16,6 +17,7 @@ type Props = {
 }
 
 export function AddGroupByUrlButton({ reload }: Props) {
+  const t = useTranslations('Groups.AddByURL')
   const isDesktop = useMediaQuery('(min-width: 640px)')
   const [url, setUrl] = useState('')
   const [error, setError] = useState(false)
@@ -27,18 +29,15 @@ export function AddGroupByUrlButton({ reload }: Props) {
       <PopoverTrigger asChild>
         <Button variant="secondary">
           {/* <Plus className="w-4 h-4 mr-2" /> */}
-          <>Add by URL</>
+          {t('button')}
         </Button>
       </PopoverTrigger>
       <PopoverContent
         align={isDesktop ? 'end' : 'start'}
         className="[&_p]:text-sm flex flex-col gap-3"
       >
-        <h3 className="font-bold">Add a group by URL</h3>
+        <h3 className="font-bold">{t('title')}</h3>
-        <p>
+        <p>{t('description')}</p>
-          If a group was shared with you, you can paste its URL here to add it
-          to your list.
-        </p>
         <form
           className="flex gap-2"
           onSubmit={async (event) => {
@@ -80,11 +79,7 @@ export function AddGroupByUrlButton({ reload }: Props) {
             )}
           </Button>
         </form>
-        {error && (
+        {error && <p className="text-destructive">{t('error')}</p>}
-          <p className="text-destructive">
-            Oops, we are not able to find the group from the URL you provided…
-          </p>
-        )}
       </PopoverContent>
     </Popover>
   )

src/app/groups/not-found.tsx

@@ -1,13 +1,15 @@
 import { Button } from '@/components/ui/button'
+import { useTranslations } from 'next-intl'
 import Link from 'next/link'
 
 export default function NotFound() {
+  const t = useTranslations('Groups.NotFound')
   return (
     <div className="flex flex-col gap-2">
-      <p>This group does not exist.</p>
+      <p>{t('text')}</p>
       <p>
         <Button asChild variant="secondary">
-          <Link href="/groups">Go to recently visited groups</Link>
+          <Link href="/groups">{t('link')}</Link>
         </Button>
       </p>
     </div>

src/app/groups/recent-group-list-card.tsx

@@ -23,6 +23,7 @@ import { ToastAction } from '@/components/ui/toast'
 import { useToast } from '@/components/ui/use-toast'
 import { StarFilledIcon } from '@radix-ui/react-icons'
 import { Calendar, MoreHorizontal, Star, Users } from 'lucide-react'
+import { useLocale, useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 import { SetStateAction } from 'react'
@@ -37,7 +38,9 @@ export function RecentGroupListCard({
   setState: (state: SetStateAction<RecentGroupsState>) => void
 }) {
   const router = useRouter()
+  const locale = useLocale()
   const toast = useToast()
+  const t = useTranslations('Groups')
 
   const details =
     state.status === 'complete'
@@ -118,12 +121,11 @@ export function RecentGroupListCard({
                           groups: state.groups.filter((g) => g.id !== group.id),
                         })
                         toast.toast({
-                          title: 'Group has been removed',
+                          title: t('RecentRemovedToast.title'),
-                          description:
+                          description: t('RecentRemovedToast.description'),
-                            'The group was removed from your recent groups list.',
                           action: (
                             <ToastAction
-                              altText="Undo group removal"
+                              altText={t('RecentRemovedToast.undoAlt')}
                               onClick={() => {
                                 saveRecentGroup(group)
                                 setState({
@@ -132,13 +134,13 @@ export function RecentGroupListCard({
                                 })
                               }}
                             >
-                              Undo
+                              {t('RecentRemovedToast.undo')}
                             </ToastAction>
                           ),
                         })
                       }}
                     >
-                      Remove from recent groups
+                      {t('removeRecent')}
                     </DropdownMenuItem>
                     <DropdownMenuItem
                       onClick={(event) => {
@@ -152,7 +154,7 @@ export function RecentGroupListCard({
                         refreshGroupsFromStorage()
                       }}
                     >
-                      {isArchived ? <>Unarchive group</> : <>Archive group</>}
+                      {t(isArchived ? 'unarchive' : 'archive')}
                     </DropdownMenuItem>
                   </DropdownMenuContent>
                 </DropdownMenu>
@@ -168,7 +170,7 @@ export function RecentGroupListCard({
                   <div className="flex items-center">
                     <Calendar className="w-3 h-3 inline mx-1" />
                     <span>
-                      {new Date(details.createdAt).toLocaleDateString('en-US', {
+                      {new Date(details.createdAt).toLocaleDateString(locale, {
                         dateStyle: 'medium',
                       })}
                     </span>

src/app/groups/recent-group-list.tsx

@@ -10,6 +10,7 @@ import {
 import { Button } from '@/components/ui/button'
 import { getGroups } from '@/lib/api'
 import { Loader2 } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { PropsWithChildren, SetStateAction, useEffect, useState } from 'react'
 import { RecentGroupListCard } from './recent-group-list-card'
@@ -53,6 +54,7 @@ function sortGroups(
 }
 
 export function RecentGroupList() {
+  const t = useTranslations('Groups')
   const [state, setState] = useState<RecentGroupsState>({ status: 'pending' })
 
   function loadGroups() {
@@ -84,8 +86,8 @@ export function RecentGroupList() {
     return (
       <GroupsPage reload={loadGroups}>
         <p>
-          <Loader2 className="w-4 m-4 mr-2 inline animate-spin" /> Loading
+          <Loader2 className="w-4 m-4 mr-2 inline animate-spin" />{' '}
-          recent groups…
+          {t('loadingRecent')}
         </p>
       </GroupsPage>
     )
@@ -95,12 +97,12 @@ export function RecentGroupList() {
     return (
       <GroupsPage reload={loadGroups}>
         <div className="text-sm space-y-2">
-          <p>You have not visited any group recently.</p>
+          <p>{t('NoRecent.description')}</p>
           <p>
             <Button variant="link" asChild className="-m-4">
-              <Link href={`/groups/create`}>Create one</Link>
+              <Link href={`/groups/create`}>{t('NoRecent.create')}</Link>
             </Button>{' '}
-            or ask a friend to send you the link to an existing one.
+            {t('NoRecent.orAsk')}
           </p>
         </div>
       </GroupsPage>
@@ -113,7 +115,7 @@ export function RecentGroupList() {
     <GroupsPage reload={loadGroups}>
       {starredGroupInfo.length > 0 && (
         <>
-          <h2 className="mb-2">Starred groups</h2>
+          <h2 className="mb-2">{t('starred')}</h2>
           <GroupList
             groups={starredGroupInfo}
             state={state}
@@ -124,14 +126,14 @@ export function RecentGroupList() {
 
       {groupInfo.length > 0 && (
         <>
-          <h2 className="mt-6 mb-2">Recent groups</h2>
+          <h2 className="mt-6 mb-2">{t('recent')}</h2>
           <GroupList groups={groupInfo} state={state} setState={setState} />
         </>
       )}
 
       {archivedGroupInfo.length > 0 && (
         <>
-          <h2 className="mt-6 mb-2 opacity-50">Archived groups</h2>
+          <h2 className="mt-6 mb-2 opacity-50">{t('archived')}</h2>
           <div className="opacity-50">
             <GroupList
               groups={archivedGroupInfo}
@@ -172,18 +174,19 @@ function GroupsPage({
   children,
   reload,
 }: PropsWithChildren<{ reload: () => void }>) {
+  const t = useTranslations('Groups')
   return (
     <>
       <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-2">
         <h1 className="font-bold text-2xl flex-1">
-          <Link href="/groups">My groups</Link>
+          <Link href="/groups">{t('myGroups')}</Link>
         </h1>
         <div className="flex gap-2">
           <AddGroupByUrlButton reload={reload} />
           <Button asChild>
             <Link href="/groups/create">
               {/* <Plus className="w-4 h-4 mr-2" /> */}
-              <>Create</>
+              {t('create')}
             </Link>
           </Button>
         </div>

src/app/layout.tsx

@@ -1,4 +1,5 @@
 import { ApplePwaSplash } from '@/app/apple-pwa-splash'
+import { LocaleSwitcher } from '@/components/locale-switcher'
 import { ProgressBar } from '@/components/progress-bar'
 import { ThemeProvider } from '@/components/theme-provider'
 import { ThemeToggle } from '@/components/theme-toggle'
@@ -6,6 +7,8 @@ import { Button } from '@/components/ui/button'
 import { Toaster } from '@/components/ui/toaster'
 import { env } from '@/lib/env'
 import type { Metadata, Viewport } from 'next'
+import { NextIntlClientProvider, useTranslations } from 'next-intl'
+import { getLocale, getMessages } from 'next-intl/server'
 import Image from 'next/image'
 import Link from 'next/link'
 import { Suspense } from 'react'
@@ -59,93 +62,109 @@ export const viewport: Viewport = {
   themeColor: '#047857',
 }
 
-export default function RootLayout({
+function Content({ children }: { children: React.ReactNode }) {
-  children,
+  const t = useTranslations()
-}: {
-  children: React.ReactNode
-}) {
   return (
-    <html lang="en" suppressHydrationWarning>
+    <>
-      <ApplePwaSplash icon="/logo-with-text.png" color="#027756" />
+      <header className="fixed top-0 left-0 right-0 h-16 flex justify-between bg-white dark:bg-gray-950 bg-opacity-50 dark:bg-opacity-50 p-2 border-b backdrop-blur-sm z-50">
-      <body className="pt-16 min-h-[100dvh] flex flex-col items-stretch bg-slate-50 bg-opacity-30 dark:bg-background">
+        <Link
-        <ThemeProvider
+          className="flex items-center gap-2 hover:scale-105 transition-transform"
-          attribute="class"
+          href="/"
-          defaultTheme="system"
-          enableSystem
-          disableTransitionOnChange
         >
-          <Suspense>
+          <h1>
-            <ProgressBar />
+            <Image
-          </Suspense>
+              src="/logo-with-text.png"
-          <header className="fixed top-0 left-0 right-0 h-16 flex justify-between bg-white dark:bg-gray-950 bg-opacity-50 dark:bg-opacity-50 p-2 border-b backdrop-blur-sm z-50">
+              className="m-1 h-auto w-auto"
-            <Link
+              width={(35 * 522) / 180}
-              className="flex items-center gap-2 hover:scale-105 transition-transform"
+              height={35}
-              href="/"
+              alt="Spliit"
-            >
+            />
-              <h1>
+          </h1>
-                <Image
+        </Link>
-                  src="/logo-with-text.png"
+        <div role="navigation" aria-label="Menu" className="flex">
-                  className="m-1 h-auto w-auto"
+          <ul className="flex items-center text-sm">
-                  width={(35 * 522) / 180}
+            <li>
-                  height={35}
+              <Button variant="ghost" asChild className="-my-3 text-primary">
-                  alt="Spliit"
+                <Link href="/groups">{t('Header.groups')}</Link>
-                />
+              </Button>
-              </h1>
+            </li>
+            <li>
+              <LocaleSwitcher />
+            </li>
+            <li>
+              <ThemeToggle />
+            </li>
+          </ul>
+        </div>
+      </header>
+
+      <div className="flex-1 flex flex-col">{children}</div>
+
+      <footer className="sm:p-8 md:p-16 sm:mt-16 sm:text-sm md:text-base md:mt-32 bg-slate-50 dark:bg-card border-t p-6 mt-8 flex flex-col sm:flex-row sm:justify-between gap-4 text-xs [&_a]:underline">
+        <div className="flex flex-col space-y-2">
+          <div className="sm:text-lg font-semibold text-base flex space-x-2 items-center">
+            <Link className="flex items-center gap-2" href="/">
+              <Image
+                src="/logo-with-text.png"
+                className="m-1 h-auto w-auto"
+                width={(35 * 522) / 180}
+                height={35}
+                alt="Spliit"
+              />
             </Link>
-            <div role="navigation" aria-label="Menu" className="flex">
+          </div>
-              <ul className="flex items-center text-sm">
+          <div className="flex flex-col space-y a--no-underline-text-white">
-                <li>
+            <span>{t('Footer.madeIn')}</span>
-                  <Button
+            <span>
-                    variant="ghost"
+              {t.rich('Footer.builtBy', {
-                    asChild
+                author: (txt) => (
-                    className="-my-3 text-primary"
-                  >
-                    <Link href="/groups">Groups</Link>
-                  </Button>
-                </li>
-                <li>
-                  <ThemeToggle />
-                </li>
-              </ul>
-            </div>
-          </header>
-
-          <div className="flex-1 flex flex-col">{children}</div>
-
-          <footer className="sm:p-8 md:p-16 sm:mt-16 sm:text-sm md:text-base md:mt-32 bg-slate-50 dark:bg-card border-t p-6 mt-8 flex flex-col sm:flex-row sm:justify-between gap-4 text-xs [&_a]:underline">
-            <div className="flex flex-col space-y-2">
-              <div className="sm:text-lg font-semibold text-base flex space-x-2 items-center">
-                <Link className="flex items-center gap-2" href="/">
-                  <Image
-                    src="/logo-with-text.png"
-                    className="m-1 h-auto w-auto"
-                    width={(35 * 522) / 180}
-                    height={35}
-                    alt="Spliit"
-                  />
-                </Link>
-              </div>
-              <div className="flex flex-col space-y a--no-underline-text-white">
-                <span>Made in Montréal, Québec 🇨🇦</span>
-                <span>
-                  Built by{' '}
                   <a href="https://scastiel.dev" target="_blank" rel="noopener">
-                    Sebastien Castiel
+                    {txt}
-                  </a>{' '}
+                  </a>
-                  and{' '}
+                ),
+                source: (txt) => (
                   <a
                     href="https://github.com/spliit-app/spliit/graphs/contributors"
                     target="_blank"
                     rel="noopener"
                   >
-                    contributors
+                    {txt}
                   </a>
-                </span>
+                ),
-              </div>
+              })}
-            </div>
+            </span>
-          </footer>
+          </div>
-          <Toaster />
+        </div>
-        </ThemeProvider>
+      </footer>
+      <Toaster />
+    </>
+  )
+}
+
+export default async function RootLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  const locale = await getLocale()
+  const messages = await getMessages()
+  return (
+    <html lang={locale} suppressHydrationWarning>
+      <ApplePwaSplash icon="/logo-with-text.png" color="#027756" />
+      <body className="pt-16 min-h-[100dvh] flex flex-col items-stretch bg-slate-50 bg-opacity-30 dark:bg-background">
+        <NextIntlClientProvider messages={messages}>
+          <ThemeProvider
+            attribute="class"
+            defaultTheme="system"
+            enableSystem
+            disableTransitionOnChange
+          >
+            <Suspense>
+              <ProgressBar />
+            </Suspense>
+            <Content>{children}</Content>
+          </ThemeProvider>
+        </NextIntlClientProvider>
       </body>
     </html>
   )

src/components/category-selector.tsx

@@ -17,6 +17,7 @@ import {
 } from '@/components/ui/popover'
 import { useMediaQuery } from '@/lib/hooks'
 import { Category } from '@prisma/client'
+import { useTranslations } from 'next-intl'
 import { forwardRef, useEffect, useState } from 'react'
 
 type Props = {
@@ -100,6 +101,7 @@ function CategoryCommand({
   categories: Category[]
   onValueChange: (categoryId: Category['id']) => void
 }) {
+  const t = useTranslations('Categories')
   const categoriesByGroup = categories.reduce<Record<string, Category[]>>(
     (acc, category) => ({
       ...acc,
@@ -110,16 +112,18 @@ function CategoryCommand({
 
   return (
     <Command>
-      <CommandInput placeholder="Search category..." className="text-base" />
+      <CommandInput placeholder={t('search')} className="text-base" />
-      <CommandEmpty>No category found.</CommandEmpty>
+      <CommandEmpty>{t('noCategory')}</CommandEmpty>
       <div className="w-full max-h-[300px] overflow-y-auto">
         {Object.entries(categoriesByGroup).map(
           ([group, groupCategories], index) => (
-            <CommandGroup key={index} heading={group}>
+            <CommandGroup key={index} heading={t(`${group}.heading`)}>
               {groupCategories.map((category) => (
                 <CommandItem
                   key={category.id}
-                  value={`${category.id} ${category.grouping} ${category.name}`}
+                  value={`${category.id} ${t(
+                    `${category.grouping}.heading`,
+                  )} ${t(`${category.grouping}.${category.name}`)}`}
                   onSelect={(currentValue) => {
                     const id = Number(currentValue.split(' ')[0])
                     onValueChange(id)
@@ -169,10 +173,11 @@ const CategoryButton = forwardRef<HTMLButtonElement, CategoryButtonProps>(
 CategoryButton.displayName = 'CategoryButton'
 
 function CategoryLabel({ category }: { category: Category }) {
+  const t = useTranslations('Categories')
   return (
     <div className="flex items-center gap-3">
       <CategoryIcon category={category} className="w-4 h-4" />
-      {category.name}
+      {t(`${category.grouping}.${category.name}`)}
     </div>
   )
 }

src/components/delete-popup.tsx

@@ -1,6 +1,7 @@
 'use client'
 
 import { Trash2 } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 import { AsyncButton } from './async-button'
 import { Button } from './ui/button'
 import {
@@ -14,20 +15,18 @@ import {
 } from './ui/dialog'
 
 export function DeletePopup({ onDelete }: { onDelete: () => Promise<void> }) {
+  const t = useTranslations('ExpenseForm.DeletePopup')
   return (
     <Dialog>
       <DialogTrigger asChild>
         <Button variant="destructive">
           <Trash2 className="w-4 h-4 mr-2" />
-          Delete
+          {t('label')}
         </Button>
       </DialogTrigger>
       <DialogContent>
-        <DialogTitle>Delete this expense?</DialogTitle>
+        <DialogTitle>{t('title')}</DialogTitle>
-        <DialogDescription>
+        <DialogDescription>{t('description')}</DialogDescription>
-          Do you really want to delete this expense? This action is
-          irreversible.
-        </DialogDescription>
         <DialogFooter className="flex flex-col gap-2">
           <AsyncButton
             type="button"
@@ -35,10 +34,10 @@ export function DeletePopup({ onDelete }: { onDelete: () => Promise<void> }) {
             loadingContent="Deleting…"
             action={onDelete}
           >
-            Yes
+            {t('yes')}
           </AsyncButton>
           <DialogClose asChild>
-            <Button variant={'secondary'}>Cancel</Button>
+            <Button variant={'secondary'}>{t('cancel')}</Button>
           </DialogClose>
         </DialogFooter>
       </DialogContent>

src/components/expense-documents-input.tsx

@@ -19,6 +19,7 @@ import { randomId } from '@/lib/api'
 import { ExpenseFormValues } from '@/lib/schemas'
 import { formatFileSize } from '@/lib/utils'
 import { Loader2, Plus, Trash, X } from 'lucide-react'
+import { useLocale, useTranslations } from 'next-intl'
 import { getImageData, usePresignedUpload } from 'next-s3-upload'
 import Image from 'next/image'
 import { useEffect, useState } from 'react'
@@ -31,6 +32,8 @@ type Props = {
 const MAX_FILE_SIZE = 5 * 1024 ** 2
 
 export function ExpenseDocumentsInput({ documents, updateDocuments }: Props) {
+  const locale = useLocale()
+  const t = useTranslations('ExpenseDocumentsInput')
   const [pending, setPending] = useState(false)
   const { FileInput, openFileDialog, uploadToS3 } = usePresignedUpload() // use presigned uploads to addtionally support providers other than AWS
   const { toast } = useToast()
@@ -38,10 +41,11 @@ export function ExpenseDocumentsInput({ documents, updateDocuments }: Props) {
   const handleFileChange = async (file: File) => {
     if (file.size > MAX_FILE_SIZE) {
       toast({
-        title: 'The file is too big',
+        title: t('TooBigToast.title'),
-        description: `The maximum file size you can upload is ${formatFileSize(
+        description: t('TooBigToast.description', {
-          MAX_FILE_SIZE,
+          maxSize: formatFileSize(MAX_FILE_SIZE, locale),
-        )}. Yours is ${formatFileSize(file.size)}.`,
+          size: formatFileSize(file.size, locale),
+        }),
         variant: 'destructive',
       })
       return
@@ -57,13 +61,15 @@ export function ExpenseDocumentsInput({ documents, updateDocuments }: Props) {
       } catch (err) {
         console.error(err)
         toast({
-          title: 'Error while uploading document',
+          title: t('ErrorToast.title'),
-          description:
+          description: t('ErrorToast.description'),
-            'Something wrong happened when uploading the document. Please retry later or select a different file.',
           variant: 'destructive',
           action: (
-            <ToastAction altText="Retry" onClick={() => upload()}>
+            <ToastAction
-              Retry
+              altText={t('ErrorToast.retry')}
+              onClick={() => upload()}
+            >
+              {t('ErrorToast.retry')}
             </ToastAction>
           ),
         })

src/components/expense-form.tsx

@@ -44,6 +44,7 @@ import {
 import { cn } from '@/lib/utils'
 import { zodResolver } from '@hookform/resolvers/zod'
 import { Save } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useSearchParams } from 'next/navigation'
 import { useEffect, useState } from 'react'
@@ -71,9 +72,6 @@ const enforceCurrencyPattern = (value: string) =>
     .replace(/#/, '.') // change back # to dot
     .replace(/[^-\d.]/g, '') // remove all non-numeric characters
 
-const capitalize = (value: string) =>
-  value.charAt(0).toUpperCase() + value.slice(1)
-
 const getDefaultSplittingOptions = (group: Props['group']) => {
   const defaultValue = {
     splitMode: 'EVENLY' as const,
@@ -154,6 +152,7 @@ export function ExpenseForm({
   onDelete,
   runtimeFeatureFlags,
 }: Props) {
+  const t = useTranslations('ExpenseForm')
   const isCreate = expense === undefined
   const searchParams = useSearchParams()
   const getSelectedPayer = (field?: { value: string }) => {
@@ -249,7 +248,7 @@ export function ExpenseForm({
     Set<string>
   >(new Set())
 
-  const sExpense = isIncome ? 'income' : 'expense'
+  const sExpense = isIncome ? 'Income' : 'Expense'
   const sPaid = isIncome ? 'received' : 'paid'
 
   useEffect(() => {
@@ -322,7 +321,9 @@ export function ExpenseForm({
       <form onSubmit={form.handleSubmit(submit)}>
         <Card>
           <CardHeader>
-            <CardTitle>{(isCreate ? 'Create ' : 'Edit ') + sExpense}</CardTitle>
+            <CardTitle>
+              {t(`${sExpense}.${isCreate ? 'create' : 'edit'}`)}
+            </CardTitle>
           </CardHeader>
           <CardContent className="grid sm:grid-cols-2 gap-6">
             <FormField
@@ -330,10 +331,10 @@ export function ExpenseForm({
               name="title"
               render={({ field }) => (
                 <FormItem className="">
-                  <FormLabel>{capitalize(sExpense)} title</FormLabel>
+                  <FormLabel>{t(`${sExpense}.TitleField.label`)}</FormLabel>
                   <FormControl>
                     <Input
-                      placeholder="Monday evening restaurant"
+                      placeholder={t(`${sExpense}.TitleField.placeholder`)}
                       className="text-base"
                       {...field}
                       onBlur={async () => {
@@ -350,7 +351,7 @@ export function ExpenseForm({
                     />
                   </FormControl>
                   <FormDescription>
-                    Enter a description for the {sExpense}.
+                    {t(`${sExpense}.TitleField.description`)}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -362,7 +363,7 @@ export function ExpenseForm({
               name="expenseDate"
               render={({ field }) => (
                 <FormItem className="sm:order-1">
-                  <FormLabel>{capitalize(sExpense)} date</FormLabel>
+                  <FormLabel>{t(`${sExpense}.DateField.label`)}</FormLabel>
                   <FormControl>
                     <Input
                       className="date-base"
@@ -374,7 +375,7 @@ export function ExpenseForm({
                     />
                   </FormControl>
                   <FormDescription>
-                    Enter the date the {sExpense} was {sPaid}.
+                    {t(`${sExpense}.DateField.description`)}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -386,7 +387,7 @@ export function ExpenseForm({
               name="amount"
               render={({ field: { onChange, ...field } }) => (
                 <FormItem className="sm:order-3">
-                  <FormLabel>Amount</FormLabel>
+                  <FormLabel>{t('amountField.label')}</FormLabel>
                   <div className="flex items-baseline gap-2">
                     <span>{group.currency}</span>
                     <FormControl>
@@ -426,7 +427,9 @@ export function ExpenseForm({
                             />
                           </FormControl>
                           <div>
-                            <FormLabel>This is a reimbursement</FormLabel>
+                            <FormLabel>
+                              {t('isReimbursementField.label')}
+                            </FormLabel>
                           </div>
                         </FormItem>
                       )}
@@ -441,7 +444,7 @@ export function ExpenseForm({
               name="category"
               render={({ field }) => (
                 <FormItem className="order-3 sm:order-2">
-                  <FormLabel>Category</FormLabel>
+                  <FormLabel>{t('categoryField.label')}</FormLabel>
                   <CategorySelector
                     categories={categories}
                     defaultValue={
@@ -451,7 +454,7 @@ export function ExpenseForm({
                     isLoading={isCategoryLoading}
                   />
                   <FormDescription>
-                    Select the {sExpense} category.
+                    {t(`${sExpense}.categoryFieldDescription`)}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -463,7 +466,7 @@ export function ExpenseForm({
               name="paidBy"
               render={({ field }) => (
                 <FormItem className="sm:order-5">
-                  <FormLabel>{capitalize(sPaid)} by</FormLabel>
+                  <FormLabel>{t(`${sExpense}.paidByField.label`)}</FormLabel>
                   <Select
                     onValueChange={field.onChange}
                     defaultValue={getSelectedPayer(field)}
@@ -480,7 +483,7 @@ export function ExpenseForm({
                     </SelectContent>
                   </Select>
                   <FormDescription>
-                    Select the participant who {sPaid} the {sExpense}.
+                    {t(`${sExpense}.paidByField.description`)}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -491,7 +494,7 @@ export function ExpenseForm({
               name="notes"
               render={({ field }) => (
                 <FormItem className="sm:order-6">
-                  <FormLabel>Notes</FormLabel>
+                  <FormLabel>{t('notesField.label')}</FormLabel>
                   <FormControl>
                     <Textarea className="text-base" {...field} />
                   </FormControl>
@@ -504,7 +507,7 @@ export function ExpenseForm({
         <Card className="mt-4">
           <CardHeader>
             <CardTitle className="flex justify-between">
-              <span>{capitalize(sPaid)} for</span>
+              <span>{t(`${sExpense}.paidFor.title`)}</span>
               <Button
                 variant="link"
                 type="button"
@@ -530,14 +533,14 @@ export function ExpenseForm({
               >
                 {form.getValues().paidFor.length ===
                 group.participants.length ? (
-                  <>Select none</>
+                  <>{t('selectNone')}</>
                 ) : (
-                  <>Select all</>
+                  <>{t('selectAll')}</>
                 )}
               </Button>
             </CardTitle>
             <CardDescription>
-              Select who the {sExpense} was {sPaid} for.
+              {t(`${sExpense}.paidFor.description`)}
             </CardDescription>
           </CardHeader>
           <CardContent>
@@ -602,7 +605,9 @@ export function ExpenseForm({
                                       })}
                                     >
                                       {match(form.getValues().splitMode)
-                                        .with('BY_SHARES', () => <>share(s)</>)
+                                        .with('BY_SHARES', () => (
+                                          <>{t('shares')}</>
+                                        ))
                                         .with('BY_PERCENTAGE', () => <>%</>)
                                         .with('BY_AMOUNT', () => (
                                           <>{group.currency}</>
@@ -700,7 +705,7 @@ export function ExpenseForm({
             >
               <CollapsibleTrigger asChild>
                 <Button variant="link" className="-mx-4">
-                  Advanced splitting options…
+                  {t('advancedOptions')}
                 </Button>
               </CollapsibleTrigger>
               <CollapsibleContent>
@@ -710,7 +715,7 @@ export function ExpenseForm({
                     name="splitMode"
                     render={({ field }) => (
                       <FormItem>
-                        <FormLabel>Split mode</FormLabel>
+                        <FormLabel>{t('SplitModeField.label')}</FormLabel>
                         <FormControl>
                           <Select
                             onValueChange={(value) => {
@@ -726,21 +731,23 @@ export function ExpenseForm({
                               <SelectValue />
                             </SelectTrigger>
                             <SelectContent>
-                              <SelectItem value="EVENLY">Evenly</SelectItem>
+                              <SelectItem value="EVENLY">
+                                {t('SplitModeField.evenly')}
+                              </SelectItem>
                               <SelectItem value="BY_SHARES">
-                                Unevenly – By shares
+                                {t('SplitModeField.byShares')}
                               </SelectItem>
                               <SelectItem value="BY_PERCENTAGE">
-                                Unevenly – By percentage
+                                {t('SplitModeField.byPercentage')}
                               </SelectItem>
                               <SelectItem value="BY_AMOUNT">
-                                Unevenly – By amount
+                                {t('SplitModeField.byAmount')}
                               </SelectItem>
                             </SelectContent>
                           </Select>
                         </FormControl>
                         <FormDescription>
-                          Select how to split the {sExpense}.
+                          {t(`${sExpense}.splitModeDescription`)}
                         </FormDescription>
                       </FormItem>
                     )}
@@ -758,7 +765,7 @@ export function ExpenseForm({
                         </FormControl>
                         <div>
                           <FormLabel>
-                            Save as default splitting options
+                            {t('SplitModeField.saveAsDefault')}
                           </FormLabel>
                         </div>
                       </FormItem>
@@ -774,10 +781,10 @@ export function ExpenseForm({
           <Card className="mt-4">
             <CardHeader>
               <CardTitle className="flex justify-between">
-                <span>Attach documents</span>
+                <span>{t('attachDocuments')}</span>
               </CardTitle>
               <CardDescription>
-                See and attach receipts to the {sExpense}.
+                {t(`${sExpense}.attachDescription`)}
               </CardDescription>
             </CardHeader>
             <CardContent>
@@ -796,11 +803,9 @@ export function ExpenseForm({
         )}
 
         <div className="flex mt-4 gap-2">
-          <SubmitButton
+          <SubmitButton loadingContent={t(isCreate ? 'creating' : 'saving')}>
-            loadingContent={isCreate ? <>Creating…</> : <>Saving…</>}
-          >
             <Save className="w-4 h-4 mr-2" />
-            {isCreate ? <>Create</> : <>Save</>}
+            {t(isCreate ? 'create' : 'save')}
           </SubmitButton>
           {!isCreate && onDelete && (
             <DeletePopup
@@ -808,7 +813,7 @@ export function ExpenseForm({
             ></DeletePopup>
           )}
           <Button variant="ghost" asChild>
-            <Link href={`/groups/${group.id}`}>Cancel</Link>
+            <Link href={`/groups/${group.id}`}>{t('cancel')}</Link>
           </Button>
         </div>
       </form>

src/components/group-form.tsx

@@ -35,6 +35,7 @@ import { getGroup } from '@/lib/api'
 import { GroupFormValues, groupFormSchema } from '@/lib/schemas'
 import { zodResolver } from '@hookform/resolvers/zod'
 import { Save, Trash2 } from 'lucide-react'
+import { useTranslations } from 'next-intl'
 import Link from 'next/link'
 import { useEffect, useState } from 'react'
 import { useFieldArray, useForm } from 'react-hook-form'
@@ -53,6 +54,7 @@ export function GroupForm({
   onSubmit,
   protectedParticipantIds = [],
 }: Props) {
+  const t = useTranslations('GroupForm')
   const form = useForm<GroupFormValues>({
     resolver: zodResolver(groupFormSchema),
     defaultValues: group
@@ -64,7 +66,11 @@ export function GroupForm({
       : {
           name: '',
           currency: '',
-          participants: [{ name: 'John' }, { name: 'Jane' }, { name: 'Jack' }],
+          participants: [
+            { name: t('Participants.John') },
+            { name: t('Participants.Jane') },
+            { name: t('Participants.Jack') },
+          ],
         },
   })
   const { fields, append, remove } = useFieldArray({
@@ -79,10 +85,10 @@ export function GroupForm({
       const currentActiveUser =
         fields.find(
           (f) => f.id === localStorage.getItem(`${group?.id}-activeUser`),
-        )?.name || 'None'
+        )?.name || t('Settings.ActiveUserField.none')
       setActiveUser(currentActiveUser)
     }
-  }, [activeUser, fields, group?.id])
+  }, [t, activeUser, fields, group?.id])
 
   const updateActiveUser = () => {
     if (!activeUser) return
@@ -111,7 +117,7 @@ export function GroupForm({
       >
         <Card className="mb-4">
           <CardHeader>
-            <CardTitle>Group information</CardTitle>
+            <CardTitle>{t('title')}</CardTitle>
           </CardHeader>
           <CardContent className="grid grid-cols-1 sm:grid-cols-2 gap-4">
             <FormField
@@ -119,16 +125,16 @@ export function GroupForm({
               name="name"
               render={({ field }) => (
                 <FormItem>
-                  <FormLabel>Group name</FormLabel>
+                  <FormLabel>{t('NameField.label')}</FormLabel>
                   <FormControl>
                     <Input
                       className="text-base"
-                      placeholder="Summer vacations"
+                      placeholder={t('NameField.placeholder')}
                       {...field}
                     />
                   </FormControl>
                   <FormDescription>
-                    Enter a name for your group.
+                    {t('NameField.description')}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -140,17 +146,17 @@ export function GroupForm({
               name="currency"
               render={({ field }) => (
                 <FormItem>
-                  <FormLabel>Currency symbol</FormLabel>
+                  <FormLabel>{t('CurrencyField.label')}</FormLabel>
                   <FormControl>
                     <Input
                       className="text-base"
-                      placeholder="$, €, £…"
+                      placeholder={t('CurrencyField.placeholder')}
                       max={5}
                       {...field}
                     />
                   </FormControl>
                   <FormDescription>
-                    We’ll use it to display amounts.
+                    {t('CurrencyField.description')}
                   </FormDescription>
                   <FormMessage />
                 </FormItem>
@@ -161,10 +167,8 @@ export function GroupForm({
 
         <Card className="mb-4">
           <CardHeader>
-            <CardTitle>Participants</CardTitle>
+            <CardTitle>{t('Participants.title')}</CardTitle>
-            <CardDescription>
+            <CardDescription>{t('Participants.description')}</CardDescription>
-              Enter the name for each participant
-            </CardDescription>
           </CardHeader>
           <CardContent>
             <ul className="flex flex-col gap-2">
@@ -183,7 +187,7 @@ export function GroupForm({
                             <Input
                               className="text-base"
                               {...field}
-                              placeholder="New"
+                              placeholder={t('Participants.new')}
                             />
                             {item.id &&
                             protectedParticipantIds.includes(item.id) ? (
@@ -203,8 +207,7 @@ export function GroupForm({
                                   align="end"
                                   className="text-sm"
                                 >
-                                  This participant is part of expenses, and can
+                                  {t('Participants.protectedParticipant')}
-                                  not be removed.
                                 </HoverCardContent>
                               </HoverCard>
                             ) : (
@@ -236,24 +239,21 @@ export function GroupForm({
               }}
               type="button"
             >
-              Add participant
+              {t('Participants.add')}
             </Button>
           </CardFooter>
         </Card>
 
         <Card className="mb-4">
           <CardHeader>
-            <CardTitle>Local settings</CardTitle>
+            <CardTitle>{t('Settings.title')}</CardTitle>
-            <CardDescription>
+            <CardDescription>{t('Settings.description')}</CardDescription>
-              These settings are set per-device, and are used to customize your
-              experience.
-            </CardDescription>
           </CardHeader>
           <CardContent>
             <div className="grid sm:grid-cols-2 gap-4">
               {activeUser !== null && (
                 <FormItem>
-                  <FormLabel>Active user</FormLabel>
+                  <FormLabel>{t('Settings.ActiveUserField.label')}</FormLabel>
                   <FormControl>
                     <Select
                       onValueChange={(value) => {
@@ -262,10 +262,17 @@ export function GroupForm({
                       defaultValue={activeUser}
                     >
                       <SelectTrigger>
-                        <SelectValue placeholder="Select a participant" />
+                        <SelectValue
+                          placeholder={t(
+                            'Settings.ActiveUserField.placeholder',
+                          )}
+                        />
                       </SelectTrigger>
                       <SelectContent>
-                        {[{ name: 'None' }, ...form.watch('participants')]
+                        {[
+                          { name: t('Settings.ActiveUserField.none') },
+                          ...form.watch('participants'),
+                        ]
                           .filter((item) => item.name.length > 0)
                           .map(({ name }) => (
                             <SelectItem key={name} value={name}>
@@ -276,7 +283,7 @@ export function GroupForm({
                     </Select>
                   </FormControl>
                   <FormDescription>
-                    User used as default for paying expenses.
+                    {t('Settings.ActiveUserField.description')}
                   </FormDescription>
                 </FormItem>
               )}
@@ -286,14 +293,15 @@ export function GroupForm({
 
         <div className="flex mt-4 gap-2">
           <SubmitButton
-            loadingContent={group ? 'Saving…' : 'Creating…'}
+            loadingContent={t(group ? 'Settings.saving' : 'Settings.creating')}
             onClick={updateActiveUser}
           >
-            <Save className="w-4 h-4 mr-2" /> {group ? <>Save</> : <> Create</>}
+            <Save className="w-4 h-4 mr-2" />{' '}
+            {t(group ? 'Settings.save' : 'Settings.create')}
           </SubmitButton>
           {!group && (
             <Button variant="ghost" asChild>
-              <Link href="/groups">Cancel</Link>
+              <Link href="/groups">{t('Settings.cancel')}</Link>
             </Button>
           )}
         </div>

src/components/locale-switcher.tsx

@@ -0,0 +1,33 @@
+'use client'
+
+import { Button } from '@/components/ui/button'
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuTrigger,
+} from '@/components/ui/dropdown-menu'
+import { locales } from '@/i18n'
+import { setUserLocale } from '@/lib/locale'
+import { useLocale, useTranslations } from 'next-intl'
+
+export function LocaleSwitcher() {
+  const t = useTranslations('Locale')
+  const locale = useLocale()
+  return (
+    <DropdownMenu>
+      <DropdownMenuTrigger asChild>
+        <Button variant="ghost" asChild className="-my-3 text-primary">
+          <span>{t(locale)}</span>
+        </Button>
+      </DropdownMenuTrigger>
+      <DropdownMenuContent>
+        {locales.map((locale) => (
+          <DropdownMenuItem key={locale} onClick={() => setUserLocale(locale)}>
+            {t(locale)}
+          </DropdownMenuItem>
+        ))}
+      </DropdownMenuContent>
+    </DropdownMenu>
+  )
+}

src/components/money.tsx

@@ -1,5 +1,6 @@
 'use client'
 import { cn, formatCurrency } from '@/lib/utils'
+import { useLocale } from 'next-intl'
 
 type Props = {
   currency: string
@@ -14,6 +15,7 @@ export function Money({
   bold = false,
   colored = false,
 }: Props) {
+  const locale = useLocale()
   return (
     <span
       className={cn(
@@ -25,7 +27,7 @@ export function Money({
         bold && 'font-bold',
       )}
     >
-      {formatCurrency(currency, amount)}
+      {formatCurrency(currency, amount, locale)}
     </span>
   )
 }

src/components/ui/form.tsx

@@ -12,6 +12,7 @@ import {
 
 import { cn } from "@/lib/utils"
 import { Label } from "@/components/ui/label"
+import { useMessages } from "next-intl"
 
 const Form = FormProvider
 
@@ -144,8 +145,18 @@ const FormMessage = React.forwardRef<
   HTMLParagraphElement,
   React.HTMLAttributes<HTMLParagraphElement>
 >(({ className, children, ...props }, ref) => {
+  const messages = useMessages()
   const { error, formMessageId } = useFormField()
-  const body = error ? String(error?.message) : children
+  let body
+  if (error) {
+    body = String(error?.message)
+    const translation = (messages.SchemaErrors as any)[body]
+    if (translation) {
+      body = translation
+    }
+  } else {
+    body = children
+  }
 
   if (!body) {
     return null

src/components/ui/search-bar.tsx

@@ -2,6 +2,7 @@ import * as React from 'react'
 
 import { Input } from '@/components/ui/input'
 import { cn } from '@/lib/utils'
+import { useTranslations } from 'next-intl'
 import { Search, XCircle } from 'lucide-react'
 
 export interface InputProps
@@ -11,6 +12,7 @@ export interface InputProps
 
 const SearchBar = React.forwardRef<HTMLInputElement, InputProps>(
   ({ className, type, onValueChange, ...props }, ref) => {
+    const t = useTranslations('Expenses')
     const [value, _setValue] = React.useState('')
 
     const setValue = (v: string) => {
@@ -28,7 +30,7 @@ const SearchBar = React.forwardRef<HTMLInputElement, InputProps>(
             className,
           )}
           ref={ref}
-          placeholder="Search for an expense…"
+          placeholder={t("searchPlaceholder")}
           value={value}
           onChange={(e) => setValue(e.target.value)}
           {...props}

src/i18n.ts

@@ -0,0 +1,16 @@
+import { getRequestConfig } from 'next-intl/server'
+import { getUserLocale } from './lib/locale'
+
+export const locales = ['en-US', 'fi'] as const
+export type Locale = (typeof locales)[number]
+export type Locales = ReadonlyArray<Locale>
+export const defaultLocale: Locale = 'en-US'
+
+export default getRequestConfig(async () => {
+  const locale = await getUserLocale()
+
+  return {
+    locale,
+    messages: (await import(`../messages/${locale}.json`)).default,
+  }
+})

src/lib/locale.ts

@@ -0,0 +1,42 @@
+'use server'
+
+import { Locale, Locales, defaultLocale, locales } from '@/i18n'
+import { match } from '@formatjs/intl-localematcher'
+import Negotiator from 'negotiator'
+import { cookies, headers } from 'next/headers'
+
+const COOKIE_NAME = 'NEXT_LOCALE'
+
+function getAcceptLanguageLocale(requestHeaders: Headers, locales: Locales) {
+  let locale
+  const languages = new Negotiator({
+    headers: {
+      'accept-language': requestHeaders.get('accept-language') || undefined,
+    },
+  }).languages()
+  try {
+    locale = match(languages, locales, defaultLocale)
+  } catch (e) {
+    // invalid language
+  }
+  return locale
+}
+
+export async function getUserLocale() {
+  let locale
+
+  // Prio 1: use existing cookie
+  locale = cookies().get(COOKIE_NAME)?.value
+
+  // Prio 2: use `accept-language` header
+  // Prio 3: use default locale
+  if (!locale) {
+    locale = getAcceptLanguageLocale(headers(), locales)
+  }
+
+  return locale
+}
+
+export async function setUserLocale(locale: Locale) {
+  cookies().set(COOKIE_NAME, locale)
+}

src/lib/schemas.ts

@@ -3,22 +3,13 @@ import * as z from 'zod'
 
 export const groupFormSchema = z
   .object({
-    name: z
+    name: z.string().min(2, 'min2').max(50, 'max50'),
-      .string()
+    currency: z.string().min(1, 'min1').max(5, 'max5'),
-      .min(2, 'Enter at least two characters.')
-      .max(50, 'Enter at most 50 characters.'),
-    currency: z
-      .string()
-      .min(1, 'Enter at least one character.')
-      .max(5, 'Enter at most five characters.'),
     participants: z
       .array(
         z.object({
           id: z.string().optional(),
-          name: z
+          name: z.string().min(2, 'min2').max(50, 'max50'),
-            .string()
-            .min(2, 'Enter at least two characters.')
-            .max(50, 'Enter at most 50 characters.'),
         }),
       )
       .min(1),
@@ -29,7 +20,7 @@ export const groupFormSchema = z
         if (otherParticipant.name === participant.name) {
           ctx.addIssue({
             code: 'custom',
-            message: 'Another participant already has this name.',
+            message: 'duplicateParticipantName',
             path: ['participants', i, 'name'],
           })
         }
@@ -42,9 +33,7 @@ export type GroupFormValues = z.infer<typeof groupFormSchema>
 export const expenseFormSchema = z
   .object({
     expenseDate: z.coerce.date(),
-    title: z
+    title: z.string({ required_error: 'titleRequired' }).min(2, 'min2'),
-      .string({ required_error: 'Please enter a title.' })
-      .min(2, 'Enter at least two characters.'),
     category: z.coerce.number().default(0),
     amount: z
       .union(
@@ -55,19 +44,16 @@ export const expenseFormSchema = z
             if (Number.isNaN(valueAsNumber))
               ctx.addIssue({
                 code: z.ZodIssueCode.custom,
-                message: 'Invalid number.',
+                message: 'invalidNumber',
               })
             return Math.round(valueAsNumber * 100)
           }),
         ],
-        { required_error: 'You must enter an amount.' },
+        { required_error: 'amountRequired' },
       )
-      .refine((amount) => amount != 1, 'The amount must not be zero.')
+      .refine((amount) => amount != 1, 'amountNotZero')
-      .refine(
+      .refine((amount) => amount <= 10_000_000_00, 'amountTenMillion'),
-        (amount) => amount <= 10_000_000_00,
+    paidBy: z.string({ required_error: 'paidByRequired' }),
-        'The amount must be lower than 10,000,000.',
-      ),
-    paidBy: z.string({ required_error: 'You must select a participant.' }),
     paidFor: z
       .array(
         z.object({
@@ -80,14 +66,14 @@ export const expenseFormSchema = z
               if (Number.isNaN(valueAsNumber))
                 ctx.addIssue({
                   code: z.ZodIssueCode.custom,
-                  message: 'Invalid number.',
+                  message: 'invalidNumber',
                 })
               return Math.round(valueAsNumber * 100)
             }),
           ]),
         }),
       )
-      .min(1, 'The expense must be paid for at least one participant.')
+      .min(1, 'paidForMin1')
       .superRefine((paidFor, ctx) => {
         let sum = 0
         for (const { shares } of paidFor) {
@@ -95,7 +81,7 @@ export const expenseFormSchema = z
           if (shares < 1) {
             ctx.addIssue({
               code: z.ZodIssueCode.custom,
-              message: 'All shares must be higher than 0.',
+              message: 'noZeroShares',
             })
           }
         }
@@ -138,7 +124,7 @@ export const expenseFormSchema = z
               : `${((sum - expense.amount) / 100).toFixed(2)} surplus`
           ctx.addIssue({
             code: z.ZodIssueCode.custom,
-            message: `Sum of amounts must equal the expense amount (${detail}).`,
+            message: 'amountSum',
             path: ['paidFor'],
           })
         }
@@ -152,7 +138,7 @@ export const expenseFormSchema = z
               : `${((sum - 10000) / 100).toFixed(0)}% surplus`
           ctx.addIssue({
             code: z.ZodIssueCode.custom,
-            message: `Sum of percentages must equal 100 (${detail})`,
+            message: 'percentageSum',
             path: ['paidFor'],
           })
         }

src/lib/utils.ts

@@ -15,9 +15,10 @@ export type DateTimeStyle = NonNullable<
 >['dateStyle']
 export function formatDate(
   date: Date,
+  locale: string,
   options: { dateStyle?: DateTimeStyle; timeStyle?: DateTimeStyle } = {},
 ) {
-  return date.toLocaleString('en-GB', {
+  return date.toLocaleString(locale, {
     ...options,
     timeZone: 'UTC',
   })
@@ -27,18 +28,25 @@ export function formatCategoryForAIPrompt(category: Category) {
   return `"${category.grouping}/${category.name}" (ID: ${category.id})`
 }
 
-export function formatCurrency(currency: string, amount: number) {
+export function formatCurrency(
-  const format = new Intl.NumberFormat('en-US', {
+  currency: string,
+  amount: number,
+  locale: string,
+) {
+  const format = new Intl.NumberFormat(locale, {
     minimumFractionDigits: 2,
     maximumFractionDigits: 2,
+    style: 'currency',
+    // '€' will be placed in correct position
+    currency: 'EUR',
   })
   const formattedAmount = format.format(amount / 100)
-  return `${currency} ${formattedAmount}`
+  return formattedAmount.replace('€', currency)
 }
 
-export function formatFileSize(size: number) {
+export function formatFileSize(size: number, locale: string) {
   const formatNumber = (num: number) =>
-    num.toLocaleString('en-US', {
+    num.toLocaleString(locale, {
       minimumFractionDigits: 0,
       maximumFractionDigits: 1,
     })