---
description: 21 supported languages and how to create or improve translations for SnapOtter using the TypeScript-enforced i18n system.
---
# Translation guide
SnapOtter ships with 21 languages out of the box. The i18n system uses a lightweight custom runtime with TypeScript-enforced locale completeness and dynamic code-splitting.
## Supported languages
| Code | Language | Native Name | Direction |
|------|----------|-------------|-----------|
| `en` | English | English | LTR |
| `zh-CN` | Chinese (Simplified) | 简体中文 | LTR |
| `zh-TW` | Chinese (Traditional) | 繁體中文 | LTR |
| `ja` | Japanese | 日本語 | LTR |
| `ko` | Korean | 한국어 | LTR |
| `es` | Spanish | Español | LTR |
| `fr` | French | Français | LTR |
| `it` | Italian | Italiano | LTR |
| `pt-BR` | Portuguese (Brazil) | Português (Brasil) | LTR |
| `de` | German | Deutsch | LTR |
| `nl` | Dutch | Nederlands | LTR |
| `sv` | Swedish | Svenska | LTR |
| `ru` | Russian | Русский | LTR |
| `pl` | Polish | Polski | LTR |
| `uk` | Ukrainian | Українська | LTR |
| `ar` | Arabic | العربية | RTL |
| `tr` | Turkish | Türkçe | LTR |
| `hi` | Hindi | हिन्दी | LTR |
| `vi` | Vietnamese | Tiếng Việt | LTR |
| `id` | Indonesian | Bahasa Indonesia | LTR |
| `th` | Thai | ไทย | LTR |
## How language detection works
SnapOtter uses a three-tier resolution order:
1. **User preference** -- stored in `localStorage("snapotter-locale")` and synced to user settings when authenticated
2. **Browser auto-detect** -- walks the `navigator.languages` array with BCP 47 prefix matching
3. **Instance default** -- the admin's `DEFAULT_LOCALE` env var (fetched from `GET /api/v1/config/locale`)
4. **English fallback** -- always available
Users can change language from:
- The **footer Globe selector** (desktop, always visible)
- The **login page** language selector (pre-auth)
- The **Settings > General** section (per-user preference)
- The **mobile sidebar** language dropdown
- The **Settings > System** section sets the instance-wide default (admin only)
## How translations work
All UI strings live in `packages/shared/src/i18n/`. The reference file is `en.ts`, which exports a typed object with every string the app uses (~1500 keys). Other languages are separate files (e.g., `de.ts`, `fr.ts`) that export the same shape.
The `TranslationKeys` type uses `DeepStringRecord` to accept any string value while enforcing the key structure. TypeScript catches missing keys in any translation file at compile time.
Only the active locale is loaded at runtime via dynamic `import()`, keeping the main bundle small.
## Using translations in components
```tsx
import { useTranslation } from "@/contexts/i18n-context";
import { format, plural } from "@/lib/format";
function MyComponent() {
const { t, locale, setLocale } = useTranslation();
return (
);
}
```
## Contributing a translation
We welcome translation PRs directly. You can improve an existing locale or add a new one.
To report a mistranslation without submitting code, open a [GitHub Issue](https://github.com/snapotter-hq/SnapOtter/issues) with the language, the incorrect string, and the suggested fix.
::: tip
Translation PRs do not require prior approval. Fork the repo, make your changes, and open a PR. See the [Contributing Guide](/guide/contributing) for the full PR process and CLA requirement.
:::
## How to create or update a translation
### 1. Fork and clone
```bash
git clone https://github.com//snapotter.git
cd snapotter
pnpm install
```
### 2. Copy the reference file (new language only)
Skip this step if you are improving an existing translation.
```bash
cp packages/shared/src/i18n/en.ts packages/shared/src/i18n/XX.ts
```
### 3. Translate the strings
Open your new file and translate every string value. Keep the object structure and keys exactly the same.
```ts
import type { TranslationKeys } from "./en.js";
export const xx: TranslationKeys = {
common: {
upload: "Your translation here",
// ... translate all entries
},
// ... translate all sections
} as const;
```
Rules:
- Do not translate object keys, only string values
- Keep `as const` at the end
- Import `TranslationKeys` from `./en.js` and type your export
- Keep `{variable}` placeholders exactly as-is
- Arrays (`rotatingPhrases`, `progressMessages`) must have the same number of entries
- Do not translate: SnapOtter, JPEG, PNG, WebP, EXIF, API, and other technical terms
### 4. Register the locale (new language only)
Add your locale to `SUPPORTED_LOCALES` in `packages/shared/src/i18n/index.ts`:
```ts
{ code: "xx", name: "Language Name", nativeName: "Native Name", dir: "ltr" },
```
### 5. Verify
```bash
pnpm typecheck # catches missing or mistyped keys
pnpm lint # formatting check
pnpm dev # manually verify strings appear correctly
```
### 6. Submit
Open a PR against `main` with a title like `feat(i18n): add Swedish translation` or `fix(i18n): correct German typos`. The CLA bot will ask you to sign on your first contribution.
## Adding new translation keys
When adding a new feature that needs new UI strings:
1. Add the new keys to `en.ts` first (the reference file)
2. Run `pnpm typecheck` -- every locale file will fail if missing the new key
3. Add the new key to all locale files (use English as a temporary fallback)
## Configuration
Set the instance default language via environment variable:
```yaml
DEFAULT_LOCALE: "de" # German as the default for all new users
```
## File reference
| File | Purpose |
|------|---------|
| `packages/shared/src/i18n/en.ts` | English strings (reference locale, ~1500 keys) |
| `packages/shared/src/i18n/index.ts` | `SUPPORTED_LOCALES`, `loadTranslations()`, type exports |
| `packages/shared/src/i18n/.ts` | Per-language translation files |
| `apps/web/src/contexts/i18n-context.tsx` | `I18nProvider`, `useTranslation()` hook |
| `apps/web/src/lib/format.ts` | `format()`, `plural()`, `formatFileSize()` helpers |
| `apps/api/src/routes/config.ts` | `GET /api/v1/config/locale` public endpoint |