i18n libraries
i18n libraries
i18n libraries
intl-ai generates translation files at build time. You choose the runtime i18n library. This page lists the supported options and their ICU compatibility.
ICU MessageFormat
Most modern i18n libraries speak ICU MessageFormat. Set processor = "icu" in intl-ai.toml to have the model emit ICU syntax; it is the contract the icu check validates.
The main exception is i18next, which uses {{var}} interpolation and plural suffixes instead of ICU syntax.
Library compatibility
| Library | Native ICU | Setup | Best for |
|---|---|---|---|
| react-intl | Yes | None | React apps that need ICU |
| @formatjs/intl | Yes | None | Framework-agnostic ICU runtime |
| lingui | Yes | Build macro | Compile-time safety, any framework |
| i18next-icu | Yes (via plugin) | Install i18next-icu |
Existing i18next apps migrating to ICU |
| vue-i18n + intl-messageformat | Yes (via custom compiler) | Custom messageCompiler |
Vue apps that need ICU |
| svelte-i18n | Partial | Manual formatter calls | Svelte apps |
| @cookbook/solid-intl | Yes | None | Solid apps that need ICU |
| @lit/localize | Partial | Community workaround | Web components |
| typesafe-i18n | No | N/A | Type-safe i18n without ICU |
| rosetta | No | N/A | Tiny footprint (298 bytes) |
| @solid-primitives/i18n | No | N/A | Minimal Solid i18n |
Configuration
Set processor = "icu" in intl-ai.toml when your target library uses ICU MessageFormat. Most modern libraries do.
If you use i18next, omit the processor setting (passthrough preserves its {{var}} style).
# intl-ai.toml
locale_dir = "locales"
source = "en"
targets = ["es", "fr"]
processor = "icu" # recommended for most libraries
Per-library guides
Choosing a library
| Need | Use |
|---|---|
| React + ICU | react-intl |
| Vue + ICU | vue-i18n with intl-messageformat compiler |
| i18next syntax (no ICU) | i18next + react-i18next |
| Compile-time type safety | lingui or typesafe-i18n |
| Smallest bundle | rosetta |
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