I18nit

⚡ Quick Reference

Package: @vielzeug/i18nit  ·  Category: I18n

Key exports: createI18n

When to use: Typed i18n with deterministic locale fallback, pluralization, async catalog loading, and reactive subscriptions.

Related: Stateit · Routeit · Fetchit

@vielzeug/i18nit is a small localization runtime for typed translation keys, plural resolution, locale loading, and framework-friendly reactivity.

Installation

pnpm

pnpm add @vielzeug/i18nit

npm

npm install @vielzeug/i18nit

yarn

yarn add @vielzeug/i18nit

Quick Start

import { createI18n } from '@vielzeug/i18nit';
import { createFormatter } from '@vielzeug/i18nit/format';

const i18n = createI18n({
  locale: 'en',
  fallback: 'en',
  catalogs: {
    en: {
      greeting: 'Hello, {name}!',
      inbox: {
        zero: 'No messages',
        one: 'One message',
        other: '{count} messages',
      },
    },
    fr: () => import('./locales/fr.json').then((m) => m.default),
  },
});

await i18n.preload('fr');
await i18n.setLocale('fr');

const greeting = i18n.t('greeting', { name: 'Alice' });
const messages = i18n.tp('inbox', 3);
const fmt = createFormatter(i18n);
const price = fmt.currency(12.5, 'EUR');

const snapshot = i18n.getSnapshot();
const unsubscribe = i18n.subscribe(
  (next) => {
    console.log(next.locale, next.version);
  },
  { immediate: true },
);

unsubscribe();

i18n.getSupportedLocales();

Why I18nit?

• Minimal API: t, tp, preload, setLocale, register, getSnapshot, subscribe, has, getSupportedLocales
• Deterministic locale fallback chain resolution
• Typed leaf and plural branch keys with explicit APIs (t and tp)
• Explicit locale source model (static messages or async loaders)
• Framework-agnostic store primitives for React, Vue, Svelte, Solid, and others
• Zero dependencies

Feature	I18nit	i18next	FormatJS
Bundle size	1.4 KB	~24 kB	~16 kB
Typed key ergonomics	✅	Partial	Partial
Deterministic fallback chain	✅	✅	✅
Async locale preload	✅	✅	✅
Runtime snapshots + subscriptions	✅	❌	❌
External formatter bridge	✅ (@vielzeug/i18nit/format)	Partial	✅
Framework agnostic	✅	✅	✅
Zero dependencies	✅	❌	❌

Use I18nit when you want a compact, typed runtime with deterministic fallback behavior and framework-agnostic reactive state.

Consider i18next or FormatJS when you need larger ecosystem plugins, message extraction pipelines, or mature framework-specific integrations.

Features

• One runtime primitive: createI18n(options)
• Explicit translation methods: t(leafKey, vars?) and tp(branchKey, count, options?)
• Explicit locale lifecycle: register, preload, setLocale
• Reactive model through snapshots: getSnapshot, subscribe
• Deterministic fallback chain using active locale plus configured fallback locales
• Unified missing handling through onMissing(info) for both key and interpolation misses
• Formatting kept separate via createFormatter(source) from @vielzeug/i18nit/format

Compatibility

Environment	Support
Browser	✅
Node.js	✅
SSR	✅
Deno	✅

Documentation

• Usage Guide
• API Reference
• Examples

See Also

• Routeit for locale-aware routes and URL state.
• Stateit for reactive locale and translation state.
• Fetchit for lazy loading translation catalogs.