4. Use Fluent For Localization

Date: 2019-12-16




The current localization (l10n) system uses the outdated and unsupported .lang format, which our l10n team would prefer to no longer support. Mozilla’s current l10n standard for products and websites is Fluent.


In order to update our l10n practices and technology and support from Mozilla’s existing l10n infrastructure and teams we will decomission the .lang system in bedrock and implement one based on Fluent. We will support both during a transition period.


Dealing with strings and templates is very different in Fluent (see the updated bedrock docs). There will be a period of developer training and adjustment to the new way of writing and previewing templates. The biggest change is that strings are no longer in the templates at all, and are instead referenced by string IDs which are in Fluent files (.ftl files).

The positive side of this change is that the developer has total control over the strings in the translation files and there are no string extraction or merge steps.