Take a set of Mozilla (Firefox, Thunderbird, SeaMonkey, etc.) localisation and migrate them to the latest Mozilla source, building XPIs and repackaging hte Windows .exe file as needed.

Please also check the page on creating a language pack on the Mozilla wiki, to stay abreast of the latest Mozilla way of doing things.


This page is only applicable to Mozilla products with its source hosted in CVS. This includes Firefox versions before 3.1 and Thunderbird versions before 3.0.

For information about working with the new source trees in Mercurial, see the Mozilla L10n Scripts page.



Contains Mozilla l10n files for available/needed language(s)


The Mozilla source tree


Contains your PO files (output from moz2po)


Where POT-archives go

Note these instructions are for building on Linux, they may work on Windows. All software should be available through your distribution. You will need to use Wine to install the Nullsoft installer and may need to sort out some path issues to get it to run correctly.

Latest Version

moz-l10n-builer is not currently distributed as part of the toolkit. You can get the latest version from Git and you will also need this minor patch to the mozilla source code.


moz-l10n-builder [language-code|ALL]



build only the supplied languages, or build ALL if specified or if no option is supplied

Your translations will not be modified.


moz-l10n-builder does the following:

  • Updates the mozilla/ directory

  • Creates POT files

  • Migrates your translations to this new POT file

  • Converts the migrated POT files to .dtd and .properties files

  • Builds XPI and .exe files

  • Performs various hacks to cater for the anomalies of file formats

  • Outputs a diff of you migrated PO files and your newly generated Mozilla l10n/ files


Currently it is too specific and not easily configurable without editing. It is also not intelligent enough to work our that you want Firefox vs Thunderbird generation. A lot of this functionality should be in the Mozilla source code itself. We hope over time that this might happen.