awesome-i18n

A curated list of i18n tools, i18n libraries, localization software, localization programs and translation management systems.

No paid or freemium services.

If you want to add something just modify README.md file ☺️ Enjoy!

👩‍🎓 Acronyms and keywords

🧐 Acronyms

i18n - internationalization
l10n - localization
xl8 - group of translation management systems
t9n - translation
g11n - globalization
m17n - multilingualization
ICU - International Components for Unicode
TMS - translation management system
GMS - globalization translation system (same thing as TMS)

🔑 Keywords

translation key - element in source code which is used by i18n library to replace it with translation message
translation - translated text or message

📦 Libraries

JavaScript / TypeScript

airbnb.io/polyglot.js - tiny i18n helper library written in JavaScript, made to work both in the browser and in CommonJS environments
VoerkaI18n - Internationalization solution for Javascript/Typescript/Vue/React/Solidjs/SvelteJs/ReactNative
eo-locale - elegant lightweight library based on Internationalization API
MDN: Intl object - documentation for standard intl object from JavaScript
MDN: i18n - internationalize your browser extension. APIs to get localized strings from locale files
facebook/fbt - internationalization framework for JavaScript designed to be not just powerful and flexible, but also simple and intuitive
FormatJS - internationalize your web apps on the client & server
FormatJS CLI - extract messages from project with FormatJS library
i18next - internationalization framework for browser or any other JavaScript environment
i18n-ally - extension for VSCode, all in one about i18n
jquery/globalize - library for i18n that leverages the official Unicode CLDR JSON data
Jed - Gettext style i18n library
lisan.js - fast and small i18n library
js-lingui - readable, automated, and optimized internationalization
npm i18n - lightweight simple translation module with dynamic JSON storage
ttag - library for translations based on ES6 template literals
typesafe-i18n - type-safe, lightweight localization library for TypeScript with no external dependencies
schummar-translate - TypeScript powered translation library for React and Node.js
messageformat - ICU MessageFormat for Javascript - i18n Plural and Gender Capable Messages
rosetta - A general purpose internationalization library in ~300 bytes (including dependencies)
Intl.js (UNMAINTAINED) - implementation of the ECMAScript Internationalization API

React / React Native

React apps and react localization is so popular so we decided to add a special section for it. Here is the list of react localization libraries:

next-translate - easy i18n for NextJS, ~1kb of size
next-intl - a minimal, but complete solution for internationalization in Next.js apps works with SSR and SSG
react-translate - internationalization for React
react-native-localize - toolbox for your React Native app localization
react-localization - simple module to localize the React interface using the same syntax used in the ReactNativeLocalization module
react-intl - internationalize your web apps with react-intl library
react-intl (CLI) - extract messages from project with FormatJS library
react-intl-hooks - small and fast library that you can use to replace FormatJS components
react-i18nify - simple i18n translation and localization components and helpers for React
react-i18next - internationalization framework for React and React Native which is based on i18next
react-i18n-mini - A tiny (~2.39 kB) internationalisation library for React
react-persian - set of react components for Persian localization
react-translated - dead simple way to add complex translations
react-localize-redux - localization library for handling translations
react-translate-component - component for React that utilizes the Counterpart module and the Interpolate component to provide multi-lingual/localized text content
react-littera - lightweight library for robust translations using hooks. Some of the key features are dynamic templates, missing reports, auto-locale detection and more
talkr - lightest i18n provider for React applications (< 1kb). Supports Typescript, provides smart autocompletion based on your own json translation files, handles complex plural rules, 0 dependencies.

VueJS

vue i18n - vue i18n is internationalization plugin for Vue.js
sweet-i18n - automatic extraction and conversion of Chinese characters in Vue and JS files based on Babel

Angular

NGX Translate - translation library for Angular

Svelte

svelte-i18n - internationalization for Svelte

Quasar.dev

Quasar i18n - official Quasar framework document page about internationalization

Java

Thymeleaf - modern server-side Java template engine for both web and standalone environments
Thymeleaf i18n docs - How to use th:texts for translations
Spring Messages - Spring Boot internationalization. LocaleResolver & LocaleChangeInterceptor example usage
Spring Boot localization - Baeldun post about using Spring Messages
i18n in Spring Boot - Stackoverflow thread about i18n in Spring Boot
Java Time Classes - Stackoverflow thread about time and timezones in Java.

Jekyll

jekyll-multiple-languages-plugin - Jekyll Multiple Languages is an internationalization plugin for Jekyll.
jekyll-i18n - Jekyll i18n is a plugin that enables simplistic multi-language site designs using Jekyll. (not maintained)

Swift (iOS & macOS)

SwiftGoogleTranslate - framework to use cloud translation API by Google in Swift

Ruby

Twitter/CLDR - implementation of the ICU that uses the Common Locale Data Repository to format dates, plurals
Ruby i18n - official internationalization API document page

Python

Python-i18n - internationalization package
deep-translator - library to translate between different languages in a simple way using multiple translators

🔦 Message and key extraction

Tools used to search translation key usage in project files. Usually they extract translation keys to some file which can be imported later to translation management system

FormatJS CLI - extract messages from project with FormatJS library
simplelocalize-cli - extract translation keys and messages from various different libraries
IntelliJ plugin for extracting i18n keys - IntelliJ IDEA plugin for extracing i18n keys

🖥 Desktop apps for translation management

Argos Translate - open source offline translation app based on OpenNMT
GNU gettext - tool for adding native language support to applications
RTranslator - simultaneous translator app for Android based on Google's API
Crow Translate - lightweight desktop translator, uses Google, Yandex and Bing translate API.
Copy Translator - cross-platform app that automatically translate texts when copied in the clipboard
ElectronJS i18n - cross-platform i18n manager
OmegaT - free translation memory application that works on all popular operating systems
LibreTranslate - self-hosted web application to translate texts
POEditor - tool for managing PO language files

📅 Utility libraries

Luxon - powerful, modern, and friendly wrapper for JavaScript dates and times (replaces momentjs)
date-fns - JS library for dates
fakenumber.org - fake phone number generator
googlei18n/libphonenumber - Google's common Java, C++ and JavaScript library for parsing, formatting, and validating international phone numbers
intl-tel-input.com - JS library for entering and validating international phone numbers

📚 Resources

Stackoverflow: Localization vs Internationalization - Localization and internationalization, what's the difference?
Stackoverflow: Daylight saving time and time-zone best practices
Blog post: Top 12 libraries for React localization - Blog post on dev.to about top 12 libraries for react localization
Blog post: Building a minimal i18n library
Blog post: Generating images with multi-language texts - article about images localization and i18n in blog post banners
Blog post: Language vs Locale - what is the difference between language and locale
Blog post: Development/Production parity for Rails i18n - blog post with a warning on using different i18n backends in development/production
Blog post: What is 'hreflang' attribute - hreflang FAQ and explanation how to use it and why it is important for SEO
Blog post: i18n with React Intl and SimpleLocalize - article demonstrates how to set up and manage translations with autogenerated translation keys with FormatJS
Github: FormatJS example project - example project built with React-intl and React
Github: i18next example project - example project built with i18next and React
Guide: Google Developers - Internationalization - official Google document page
Guide: Angular i18n - official Angular i18n document page
Guide: W3C i18n standards
Guide: Common Language Data Repository - the Unicode CLDR provides key building blocks for software to support the world's languages, with the largest and most extensive standard repository of locale data available
ICU: International Components for Unicode - ICU is a mature and widely used providing Unicode and Globalization support for software applications
Extract messages and translation keys from project files - extracting translation keys from project files. JavaScript, Android, iOS/macOS

💭 Community tips & tricks

If you have tight layouts, my rough rule of thumb is to double the English text and make sure it fits. Then you will usually have enough space for translations.
Russian and German tend to have the longest translations, and the longest words. Get familiar with the shy-hyphen  character. You put it in the word's html and it will only break the word/show the hyphen when necessary. Google “online hyphenation tool” so you know the appropriate places to break the word.
You need to translate numbers with decimals and commas because they are reversed in some languages (period appears as a comma, comma as a period).
Same goes for percent signs. Sometimes the % shows before the number, and not after. There might be a space between the number and %. It might show as %-KAL in Hungarian.
Greek question marks look like a semicolon.
Always keep datetimes in database in UTC. Always return datatimes from backend in UTC. Adjust datetimes on UI layer using timezone information from user or web browser. Accept datetimes in backend with any timezone.

🦾 Automated translation

Gengo - translation is made by real people but you can make an order using API
Google Translate
Microsoft Translator
DeepL

🍿 Videos

Internationalis(z)ing Code - Computerphile

Link: https://www.youtube.com/watch?v=0j74jcxSunY

The Problem with Time & Timezones - Computerphile

Link: https://www.youtube.com/watch?v=-5wpm-gesOY

📢 Contribute

Feel free to add or update the content!

jpomykala / awesome-i18n