core

Ngx-translate is the most widely adopted internationalization library for Angular. It loads translation JSON files, swaps languages on the fly, and provides pipes and directives for translating templates. Plain terms: it makes your Angular app work in French, Spanish, Japanese, or whatever languages your users need.

MIT license, TypeScript. The API is straightforward: TranslateModule in your app module, JSON files per language, {{ 'KEY' | translate }} in templates or TranslateService.instant('KEY') in code. Supports lazy loading of languages, parameterized translations, and a plugin system for different loaders (HTTP, PO files, etc.).

Fully free. No paid tier, no premium features. Solo to large teams: free. The decision isn't about cost, it's about whether to use this or Angular's built-in i18n. Use ngx-translate when you need runtime language switching without a page reload. Use Angular's built-in i18n when you want compile-time optimization and don't mind separate builds per language.

The catch: Angular has built-in i18n since Angular 9, and the official solution has gotten better over time. ngx-translate is still widely used because it's simpler to set up (runtime translation swapping vs. Angular's compile-time approach), but new Angular projects should evaluate the built-in i18n first. Also, ngx-translate's development has slowed. The library works, but major new features are unlikely.