npm install @ngx-translate/core @ngx-translate/http-loader

// app.module.ts
import { TranslateModule, TranslateLoader } from '@ngx-translate/core';
import { TranslateHttpLoader } from '@ngx-translate/http-loader';
import { HttpClient } from '@angular/common/http';

export function createTranslateLoader(http: HttpClient) {
  return new TranslateHttpLoader(http, './assets/i18n/', '.json');
}

@NgModule({
  imports: [
    TranslateModule.forRoot({
      loader: { provide: TranslateLoader, useFactory: createTranslateLoader, deps: [HttpClient] },
      defaultLanguage: 'en',
    }),
  ],
})
export class AppModule {}

<!-- template -->
<h1>{{ 'WELCOME.TITLE' | translate }}</h1>
<button (click)="translate.use('de')">Deutsch</button>