Simple Locale Switcher

An XUL-based extension for Mozilla Firefox, Thunderbird and the SeaMonkey suite that exposes the hidden preferences that define the preferred language for the user interface of the application.

Install

The latest public release can be found in the main page of the extension in addons.mozilla.org (AMO). Older releases, along with the changelogs and compatibility info, are listed in the versions page in AMO.

Firefox 57 and later

Being a so-called "legacy" add-on, it can't be installed in Firefox 57 (a.k.a Firefox Quantum) and later versions, where only add-ons built using the WebExtensions model are accepted. Sadly, it's not possible to port this add-on to WebExtensions.

The only remaining option for Fx users is to manage the language manually, setting the related internal preferences of the application each time.

Docs

• A (still rudely incomplete) general user guide
• A description of some advanced, hidden preferences
• All the language names for the respective locale codes used to identify language packs

Other external, related resources:

• Language packs | Firefox support
• Language packs | MozillaZine knowledge base

Contact, contribute

• Questions, bug reports and feature requests are tracked in the Issues page. You will need to have a GitHub account to post here. Alternatively, there is a thread in the MozillaZine forums open to general discussion.
• Translations are managed via the BabelZilla platform. They are done by a helpful group of volunteers. Please go there if you want to collaborate updating or starting a new localization.
• About code contributions via pull requests: before to start one, please create a new branch in your repository to accommodate your commits; it makes things easier if you need to do further amendments to your code.

License

All the source code is shared under the terms of the Mozilla Public License (MPL) 2.0.