Web Framework Integrations

npm install i18next react-i18next

langctl init --project my-app --format json --output "public/locales/{lang}.json"
langctl pull

// src/i18n.js
import i18n from 'i18next';
import { initReactI18next } from 'react-i18next';
import HttpBackend from 'i18next-http-backend';
import LanguageDetector from 'i18next-browser-languagedetector';

i18n
.use(HttpBackend)
.use(LanguageDetector)
.use(initReactI18next)
.init({
  fallbackLng: 'en',
  debug: false,
  interpolation: {
    escapeValue: false
  },
  backend: {
    loadPath: '/locales/{{lng}}.json'
  }
});

export default i18n;

// src/App.tsx
import { useTranslation } from 'react-i18next';
import './i18n';

function App() {
const { t, i18n } = useTranslation();

const changeLanguage = (lng: string) => {
  i18n.changeLanguage(lng);
};

return (
  <div>
    <h1>{t('home.welcome', { username: 'John' })}</h1>
    <p>{t('home.subtitle')}</p>

    <button onClick={() => changeLanguage('es')}>
      Español
    </button>
  </div>
);
}

npm install vue-i18n

langctl pull my-app -f nested-json -o "src/locales/{lang}.json" -l en,es

// src/i18n.ts
import { createI18n } from 'vue-i18n';
import en from './locales/en.json';
import es from './locales/es.json';

const i18n = createI18n({
locale: 'en',
fallbackLocale: 'en',
messages: { en, es }
});

export default i18n;

// main.ts
import { createApp } from 'vue';
import App from './App.vue';
import i18n from './i18n';

createApp(App).use(i18n).mount('#app');

<!-- Component.vue -->
<template>
<div>
  <h1>{{ $t('home.welcome', { username: 'John' }) }}</h1>
  <p>{{ $t('home.subtitle') }}</p>
  <button @click="changeLocale('es')">Español</button>
</div>
</template>

<script setup>
import { useI18n } from 'vue-i18n';

const { locale } = useI18n();
const changeLocale = (lang) => locale.value = lang;
</script>

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

langctl pull my-app -f json -o "src/assets/i18n/{lang}.json" -l en,es

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

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

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

// component.ts
import { TranslateService } from '@ngx-translate/core';

export class AppComponent {
constructor(private translate: TranslateService) {
  translate.setDefaultLang('en');
  translate.use('en');
}

switchLanguage(lang: string) {
  this.translate.use(lang);
}
}

// component.html
<h1>{{ 'home.welcome' | translate: {username: 'John'} }}</h1>
<p>{{ 'home.subtitle' | translate }}</p>

npm install next-i18next react-i18next i18next

langctl pull my-app -f json -o "public/locales/{lang}/common.json" -l en,es

// next-i18next.config.js
module.exports = {
i18n: {
  defaultLocale: 'en',
  locales: ['en', 'es', 'fr'],
  localeDetection: true
},
localePath: './public/locales'
};

// next.config.js
const { i18n } = require('./next-i18next.config');

module.exports = {
i18n,
};

// pages/index.tsx
import { serverSideTranslations } from 'next-i18next/serverSideTranslations';
import { useTranslation } from 'next-i18next';

export default function Home() {
const { t } = useTranslation('common');

return (
  <div>
    <h1>{t('home.welcome')}</h1>
    <p>{t('home.subtitle')}</p>
  </div>
);
}

export async function getStaticProps({ locale }) {
return {
  props: {
    ...(await serverSideTranslations(locale, ['common']))
  }
};
}

npm install svelte-i18n

langctl pull my-app -f nested-json -o "src/locales/{lang}.json" -l en,es

// src/i18n.js
import { register, init } from 'svelte-i18n';

register('en', () => import('./locales/en.json'));
register('es', () => import('./locales/es.json'));

init({
fallbackLocale: 'en',
initialLocale: 'en'
});

// App.svelte
<script>
import { _ } from 'svelte-i18n';
import './i18n';
</script>

<h1>{$_('home.welcome', { values: { username: 'John' } })}</h1>
<p>{$_('home.subtitle')}</p>

// package.json
{
"scripts": {
  "prebuild": "npm run fetch-translations",
  "build": "vite build",
  "dev": "npm run fetch-translations && vite",
  "fetch-translations": "langctl pull"
}
}

name: Build with Translations

on: [push]

jobs:
build:
  runs-on: ubuntu-latest
  steps:
    - uses: actions/checkout@v4
    - uses: actions/setup-node@v4
      with: { node-version: 22 }

    - name: Install Dependencies
      run: npm ci

    - name: Pull Translations
      env:
        LANGCTL_API_KEY: ${{ secrets.LANGCTL_API_KEY }}
      run: npx langctl@0 pull    # project, format and path come from langctl.json

    - name: Build
      run: npm run build

    - name: Deploy
      run: npm run deploy