Code	Language
`ar`	Arabic
`bn`	Bengali
`de`	German
`en`	English
`es`	Spanish
`fa`	Persian (Farsi)
`fr`	French
`hi`	Hindi
`id`	Indonesian
`it`	Italian
`ja`	Japanese
`ko`	Korean
`nl`	Dutch
`pl`	Polish
`pt`	Portuguese
`ru`	Russian
`sv`	Swedish
`th`	Thai
`tr`	Turkish
`uk`	Ukrainian
`vi`	Vietnamese
`zh`	Chinese (Simplified)

Use all built-in locales

import { betterAuth } from "better-auth";
import { i18n, locales } from "@better-auth/i18n";

export const auth = betterAuth({
  plugins: [
    i18n({ translations: locales }),
  ],
});

Use a subset of locales

import { i18n, locales } from "@better-auth/i18n";

export const auth = betterAuth({
  plugins: [
    i18n({
      translations: {
        en: locales.en,
        fr: locales.fr,
      },
    }),
  ],
});

Override specific messages

import { i18n, locales } from "@better-auth/i18n";

export const auth = betterAuth({
  plugins: [
    i18n({
      translations: {
        ...locales,
        fr: {
          ...locales.fr,
          USER_NOT_FOUND: "Membre introuvable",
        },
      },
    }),
  ],
});

Add a custom locale

import { i18n, locales } from "@better-auth/i18n";
import type { TranslationDictionary } from "@better-auth/i18n";

const myLocale: TranslationDictionary = {
  USER_NOT_FOUND: "...",
  INVALID_EMAIL_OR_PASSWORD: "...",
  // ... other error codes
};

export const auth = betterAuth({
  plugins: [
    i18n({
      translations: {
        ...locales,
        xx: myLocale,
      },
    }),
  ],
});

Documentation

For full documentation, visit better-auth.com/docs/plugins/i18n.

License

MIT