lingui/js-lingui
Js Lingui
Lingui is a JavaScript internationalization library that provides a framework-agnostic core with bindings for React, SolidJS, Svelte, Astro, and other JavaScript frameworks. It operates through a compile-time message extraction pipeline that scans source files for translatable strings, generates standard PO, JSON, or CSV catalog files, and compiles them into optimized JavaScript modules for production deployment. The library uses macro-based message definition to wrap translatable text in source code while preserving context for extraction, and includes a plural rule engine that automatically generates correct plural forms for any language using CLDR rules.
The project distinguishes itself through its AI-assisted translation capabilities, which attach descriptions and context to message keys to guide both human translators and AI assistants in producing accurate localizations. It provides reusable procedural knowledge packages that equip AI coding agents with best practices and common patterns for internationalization tasks, and serves documentation in a streamlined Markdown format optimized for AI consumption, including a real-time searchable MCP server. Lingui also offers a comprehensive CLI workflow for automating extraction, compilation, and validation of translation catalogs, with parallelized processing for faster builds and an ESLint plugin to catch common internationalization mistakes during development.
The library supports runtime locale loading that imports only the active locale's compiled catalog to minimize bundle size, and integrates with build tools like Vite and Babel to compile catalogs automatically during development and production builds. It handles ICU MessageFormat syntax for plurals, selectors, and rich-text placeholders, and allows embedding React components directly inside translated messages for complex formatting. Translations can be stored in standard PO files, CSV, JSON, or custom formats, and the library provides framework-specific hooks and components for React, SolidJS, and React Native that follow each renderer's lifecycle.
Documentation is available in Markdown format optimized for both human readers and AI tools, with an MCP server enabling real-time search for AI agents.
Features
- Internationalization and Localization - Adds translatable text to JavaScript projects using ICU MessageFormat with compile-time extraction and multi-framework support.
- JavaScript Internationalization Libraries - Adds translatable text to JavaScript apps with extraction, compilation, and runtime loading of message catalogs.
- Framework-Agnostic i18n Cores - Provides a universal internationalization engine with thin bindings for React, SolidJS, Svelte, Astro, and other JavaScript frameworks.
- Product Catalog Generators - Compiles translation catalogs into optimized JavaScript modules for production deployment.
- Source Code Translation Markers - Uses macros and components to wrap translatable text in source code for compile-time extraction.
- I18n Message Extraction - Scans source files with a CLI tool to find translatable strings and generate message catalogs.
- Client-Side Translation Components - Wraps translatable strings with components that render the correct localized version based on active language.
- Translation Catalog Compilers - Converts translation catalogs into minified JavaScript modules during the build process for production deployment.
- CLI Translation Workflow Managers - Offers a command-line interface for extracting messages, compiling catalogs, and managing translation tasks across the development pipeline.
- Translation Catalog Compilers - Compiles translation catalogs during the build process so translated text is ready to use without a separate compilation step.
- Source Code Message Extractors - Scans source files during the build process to collect translatable strings into standard PO, JSON, or CSV catalog files.
- React Internationalization Libraries - Localizes React applications using components and macros for defining and embedding rich text in messages.
- i18n Frameworks - Integrates internationalization into React applications using components and macros for defining and embedding rich text in translated messages.
- Runtime Locale Loaders - Loads compiled translation catalogs at runtime based on user preference, enabling fast localized rendering without rebuilds.
- In-App Message Translators - Wraps user-facing text with macros and components directly in UI code for extraction.
- Localized - Uses React components directly inside localized messages with JSX-like syntax.
- Inline Message Definitions - Wraps translatable text directly in source code using components and macros for easy extraction and compilation.
- Internationalization Macros - Wraps translatable text in source code using macros that preserve context for extraction and compilation.
- Message Catalog Management - Converts human-readable translation files into compact, runtime-optimized JavaScript modules.
- Runtime Validator Compilation - Compiles translation catalogs into optimized JavaScript modules for runtime loading.
- Automated String Extraction - Scans source files for translatable text and generates message catalogs with optional multithreaded processing.
- Framework-Specific Lifecycle Bindings - Provides framework-specific hooks and components that follow each renderer's lifecycle for React, SolidJS, and React Native.
- Source Code Translation Extractors - Scans source files for tagged message strings and extracts them into standard PO, CSV, or JSON catalogs.
- Pluralization Rules - Generates correct plural forms for any language automatically using CLDR plural rules without developer intervention.
- ICU Message Parsing - Parses and formats messages using ICU MessageFormat, supporting plurals, selectors, and rich-text placeholders.
- Translation Workflows - Provides a CLI to extract, compile, and validate translation messages from source code.
- Translation Macros - Wraps user-facing text in macros or components so translatable strings stay close to the UI logic and remain maintainable.
- Framework Bindings - Provides a universal internationalization core that integrates with React, SolidJS, Svelte, and other frameworks via thin bindings.
- CLI and Plugin Workflows - Uses a CLI, Vite plugin, and ESLint plugin to extract, compile, validate, and catch common errors in the internationalization pipeline.
- Localized - Embeds React components directly inside ICU MessageFormat strings for interactive localized messages.
- Framework Integrations - Provides framework-agnostic core and bindings for React, SolidJS, Svelte, and other frameworks.
- Localized Text Renderers - Provides React components and hooks to display translated messages, including rich-text content and React Server Components.
- Internationalization Utilities - Provides core internationalization functions that work in any JavaScript project.
- Automated Translation Workflows - Automates extraction, compilation, and validation of translation catalogs in CI pipelines and builds.
- Message Format Libraries - Parses and renders messages using ICU MessageFormat syntax for plurals, selectors, and rich-text placeholders.
- Multi-Framework Localization Libraries - Shares a single internationalization workflow across React, React Native, SolidJS, Astro, and Svelte.
- ICU MessageFormat Translators - Wraps translatable strings in JSX components using ICU MessageFormat syntax for extraction.
- Runtime Locale Loaders - Ships compiled catalogs and loads the correct locale at runtime for fast localized rendering.
- Internationalization Agent Skills - Equips AI coding agents with reusable procedural knowledge packages for internationalization tasks.
- AI Coding Assistant Guidance - Provides documentation files and agent skills so AI tools can correctly implement internationalization.
- Internationalization Pattern Guidance - Provides reusable procedural knowledge packages that equip AI coding agents with best practices for internationalization tasks.
- AI-Optimized Documentation - Delivers full documentation in a streamlined Markdown format that AI tools can auto-discover and parse for accurate context.
- Real-Time Documentation Indexes - Indexes the latest library documentation so AI agents can search it on demand with low token usage.
- Dynamic Locale Switching - Imports only the locale-specific message file at runtime to reduce bundle size and enable on-demand language switching.
- AI Translation Assistants - Allows developers to add descriptions and context to message keys, and provides skills files to help AI assistants apply patterns consistently.
- Context-Aware Translation Assistants - Provides context and procedural knowledge to AI assistants for consistent translation of application strings.
- Translation Key Context Providers - Attaches descriptions and context to message keys to guide AI assistants and human translators in accurate localization.
- AI-Consumable Documentation Servers - Serves static Markdown files and a real-time searchable MCP server that give AI tools accurate, up-to-date documentation content.
- AI-Optimized Documentation - Serves documentation in a streamlined Markdown format optimized for AI consumption and auto-discovery.
- Translation String Contexts - Attaches usage context to localization keys so translators and AI assistants produce accurate translations.
- AI Translation Context - Allows developers to add descriptions to message keys and install a skills package so AI assistants produce consistent, context-aware translations.
- AI Assistant Integrations - Provides documentation files and agent skills optimized for LLM context windows to guide AI assistants in internationalization tasks.
- Missing Translation Captures - Scans source files for untranslated strings and reports them as lint violations.
- Build Tool Integrations - Integrates with Vite and Babel to compile message catalogs automatically during development and production builds.
- Internationalization - Applies Lingui's macro transformations through a Babel preset when used with the Rolldown Babel plugin.
- PO File Integrations - Stores translations in portable PO files with support for JSON, CSV, and custom formats for compatibility with translation platforms.
- Internationalization Lint Validators - Checks source code with an ESLint plugin to catch common internationalization mistakes during development.
- Localization Template Generation - Extracts messages from source files and creates .pot template files for fallback.
- Automatic Language Detections - Automatically detects the user's preferred language from the browser or environment and loads the matching translation pack.
- ESLint Translation Validators - Checks source code for common i18n mistakes like missing message tags or incorrect arguments via ESLint.
- Translation Management Integrations - Stores translations in standard formats like PO, JSON, or CSV for professional translation tools.
- Standard Translation Formats - Stores translations in standard PO, CSV, JSON, or custom formats for compatibility with translation platforms.
- Usage Enforcers - Flags direct string literals in JSX that should be wrapped with a translation function.
- Translation Catalog Format Support - Stores translations in PO, CSV, JSON, or custom formats to fit existing toolchains.
- I18N - Core library for template-based internationalization.
- Internationalization - Automated and optimized internationalization for JavaScript.
