As the Firefox OS project started, one of the first main concerns was to handle internationalization and localization on the client-side. The webL10n library allows to use the *.properties format used in most Mozilla and Java-based projects in any web page, with a few extensions to implement L20n concepts without breaking the forward compatibility. Find out how easy it can be for developers to internationalize an application, and how localizers can be empowered to handle complex grammatical situations easily (e.g. pluralization rules).