index.md

---

title: i18n
slug: Mozilla/Add-ons/WebExtensions/API/i18n
page-type: webextension-api
tags:
  - API
  - Add-ons
  - Extensions
  - Interface
  - Non-standard
  - Reference
  - WebExtensions
  - i18n
browser-compat: webextensions.api.i18n

---

{{AddonSidebar}}

Functions to internationalize your extension. You can use these APIs to get localized strings from locale files packaged with your extension, find out the browser's current language, and find out the value of its Accept-Language header.

See the Internationalization page for a guide on using this API.

Types

• {{WebExtAPIRef("i18n.LanguageCode")}}

  • : A language tag such as "en-US" or "fr".

Functions

• {{WebExtAPIRef("i18n.getAcceptLanguages()")}}

  • : Gets the accept-languages of the browser. This is different from the locale used by the browser. To get the locale, use {{WebExtAPIRef('i18n.getUILanguage')}}.

• {{WebExtAPIRef("i18n.getMessage()")}}

  • : Gets the localized string for the specified message.

• {{WebExtAPIRef("i18n.getUILanguage()")}}

  • : Gets the UI language of the browser. This is different from {{WebExtAPIRef('i18n.getAcceptLanguages')}} which returns the preferred user languages.

• {{WebExtAPIRef("i18n.detectLanguage()")}}

  • : Detects the language of the provided text using the Compact Language Detector.

Browser compatibility

{{Compat}}

{{WebExtExamples("h2")}}

Note: This API is based on Chromium's chrome.i18n API. This documentation is derived from i18n.json in the Chromium code.

See also

• Internationalization: a guide to using the WebExtension i18n system.

• Locale-Specific Message reference: extensions supply locale-specific strings in files called messages.json. This page describes the format of messages.json.