I18nit

@vielzeug/i18nit is a zero-dependency internationalization library with typed keys, nested message trees, fallback chains, and async locale loading.

Installation

pnpm

pnpm add @vielzeug/i18nit

npm

npm install @vielzeug/i18nit

yarn

yarn add @vielzeug/i18nit

Quick Start

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

const i18n = createI18n({
  fallback: 'en',
  locale: 'en',
  messages: {
    de: {
      greeting: 'Hallo, {name}!',
      inbox: { one: 'Eine Nachricht', other: '{count} Nachrichten' },
    },
    en: {
      greeting: 'Hello, {name}!',
      inbox: { zero: 'No messages', one: 'One message', other: '{count} messages' },
      nav: { home: 'Home' },
    },
  },
});

i18n.t('greeting', { name: 'Alice' });
i18n.t('inbox', { count: 0 });
i18n.t('inbox', { count: 3 });

await i18n.switchLocale('de');
i18n.t('nav.home'); // falls back to en

Why I18nit?

Rolling your own i18n means hard-coded string lookups, no pluralisation, no type safety on translation keys, and no lazy loading for large locale bundles.

// Before — manual locale map (no type safety, no pluralisation)
const messages = {
  en: { greeting: 'Hello, {name}!', items: '{count} items' },
  de: { greeting: 'Hallo, {name}!' },
};
let locale = 'en';
function t(key: string, vars?: Record<string, unknown>) {
  let msg = (messages as any)[locale]?.[key] ?? key; // no type safety
  if (vars) msg = msg.replace(/{(\w+)}/g, (_: string, k: string) => String(vars[k] ?? k));
  return msg;
}

// After — I18nit
import { createI18n } from '@vielzeug/i18nit';
const i18n = createI18n<typeof messages.en>({ locale: 'en', messages });
i18n.t('greeting', { name: 'Alice' }); // typed key, typed vars
i18n.t('items', { count: 3 }); // typed + pluralised

Feature	I18nit	i18next	typesafe-i18n
Bundle size	2.3 KB	~15 kB	~1 kB
Type-safe keys	✅	❌	✅
No code generation	✅	✅	❌
Pluralisation	✅ Intl.PluralRules	✅	✅
Formatting helpers	✅ Intl-backed	✅ Plugins	❌
BCP47 locale cascade	✅	✅	❌
Async loaders	✅	✅	✅
Zero dependencies	✅	❌	✅

Use I18nit when you want type-safe translation keys with full TypeScript inference, pluralisation, and Intl-based formatting — without a code generation step.

Consider i18next if you need its large plugin ecosystem (react-i18next, backend adapters) or are migrating an existing project.

Features

• Type-safe translation keys and namespace scoping
• Dot-notation lookups with fallback chains
• Interpolation for nested vars and array tokens
• Plural messages driven by Intl.PluralRules
• Async loading (ensureLocale, switchLocale, registerLoader, reload)
• Catalog updates (add, replace) and notification batching (batch)
• Locale-bound and namespace-bound views (withLocale, scope)
• Intl formatting helpers (number, date, list, relative, currency)
• Diagnostics (onDiagnostic) and custom missing-key handling (onMissing)
• Lightweight runtime — 2.3 KB gzipped, zero dependencies

Compatibility

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

See Also

• Stateit
• Craftit
• Routeit