next-dialect

Zero-overhead i18n for Next.js. Localized strings are compiled to constants inside the chunks that use them, and only those chunks are locale-specific. No client-side catalog, no runtime lookups, no fallback chains.

Measured against a no-i18n build of the same app, the total i18n cost is +1.8 KB, flat from 600 messages to 60,000.

npm install next-dialect

Requires Next 15+ on the App Router, and React 19.

The entire API

import { t } from 'next-dialect'

<h1>{t('home.title')}</h1>
<p>{t('home.greeting', { name })}</p>
<span>{t(`status.${s}`)}</span>              // dynamic key, bounded by the static prefix

t.rich('legal.terms', {                      // ICU tags call back into components
  link: (c) => <a href="/terms">{c}</a>,
})

t.dynamic(keyFromServer, params, 'errors.')  // explicit escape hatch

t.locale                                     // current locale

t is a plain function, not a hook — the locale is invariant per rendering context, so it works in server components, client components, event handlers and plain helpers alike. There is no provider, no useT and no getT(locale): the compiler binds the locale from the [locale] segment.

Plus one config wrapper:

// next.config.mjs
import { withDialect } from 'next-dialect/config'

export default withDialect(nextConfig, {
  locales: ['en', 'nl'],
  defaultLocale: 'en',
  messages: './messages',        // JSON catalogs: en.json, nl.json, …
})

…and two commands: next-dialect build, next-dialect start.

How it works

1. Compile. Every t(...) call site in a production client bundle is replaced by its result: a bare literal for static text, a five-line formatter for {arg} messages, a precompiled ICU tree for the rest. A key the compiler cannot bound is a build error, not a silent catalog import.
2. ICU. Full MessageFormat — plurals with offset:, ordinals, selects, number/date skeletons, and tags for rich text. The parser runs at build time only; the browser gets a compact AST and a small walker over native Intl.
3. Serve. On a server, the bundle proxy rewrites only the chunks that actually contain messages, per request — framework and vendor chunks keep one shared URL for every locale. On a static host, the build forks the export into one complete site per locale.

Dev mode skips compilation entirely: runtime lookup with HMR, same evaluator.

Documentation

Full docs — getting started, API, configuration, compiler architecture and the bundle proxy — live in the repository.

License

MIT