The idea of building @ngx-runtime-i18n came from my personal experience and if I may daresay frustration at the popular options when it came to internationalisation in Angular app. Particularly in applications of scale especially at an enterprise level, it was no picnic. Among many others, one critical decision point was regarding the usage of signals which clearly was the road ahead and yet, even as we speak, not the standard for the community at large.
Most Angular i18n libraries predate signals. ngx-translate and transloco both started as RxJS-first services, and both have spent the last year retrofitting signal support on top: transloco added translateSignal by wrapping toObservable() around its existing pipeline (jsverse/transloco#781 is the tracking issue - still open, with a maintainer confirming a signals-native rewrite is in progress); ngx-translate went further in its v18 rewrite and made signals the primary API. Angular's own built-in i18n never solved this because it isn't runtime at all but a compile step that produces one build per locale, with no way to switch languages
without a page reload, which also means that local development is no party either.
I wanted the opposite starting point: build the service on signals from day one, and treat RxJS as an optional bridge for people who still need it, not the other way round. That's @ngx-runtime-i18n/angular. I18nService exposes lang(), ready(), and switching() as signals directly; t$() is a computed signal that recomputes when the language or the parameters change; there's no toSignal(this.service.stream$) anywhere in the implementation. If you do need Observables where your codebase uses existing NgRx effects, older RxJS-based code, the I18nCompatService wraps the same state as lang$/ready$ instead of the other way round.
The other piece I didn't want to compromise on was ICU. A lot of runtime i18n libraries handle "1 item" / "2 items" and stop there, which works for English and fails for Arabic (six plural forms), Polish, or Russian. formatIcu() implements plural, select, and selectordinal against the actual CLDR plural categories (zero/one/two/few/many/other), so a translator can write correct plural rules for their language instead of the library silently falling back to English-shaped logic.
SSR was the third constraint. provideRuntimeI18nSsr() seeds the resolved catalog into Angular's TransferState on the server, so the client picks up exactly what was rendered instead of re-fetching and re-resolving the language after hydration - no flash of the wrong language, no mismatch warnings.
None of this is finished in the sense that the library is done growing. It's six packages now (core, angular, primeng, material, schematics, cli), all on npm as of v2.1.0, with real but small usage so far. The parts I'd like feedback on most: route-scoped catalog loading (loadScope()/unloadScope()) for large apps with many feature modules, and whether the fallback-chain API (fallbacks: string[] on top of defaultLang) covers the cases people actually hit in multi-region products.
Repo: https://github.com/AshwinSathian/ngx-runtime-i18n
npm: https://www.npmjs.com/package/@ngx-runtime-i18n/angular
Docs: https://i18n.ashwinsathian.com/
