XULRunner is a discontinued Mozilla runtime environment. It was designed to allow developers to build standalone desktop applications using the same technologies that powered early versions of Firefox and Thunderbird—specifically (XML User Interface Language) and XPCOM (Cross Platform Component Object Model). Where to Download XULRunner for Windows
Version 41.0.2 (released October 2015) is the last official version. xulrunner download windows
The most reliable source for historical builds is the Mozilla FTP Archive . XULRunner is a discontinued Mozilla runtime environment
XULRunner is typically distributed as a ZIP archive rather than a standard .exe installer. The most reliable source for historical builds is
Below is a comprehensive guide on where to find the official downloads, how to install them, and what you need to know about the current state of XULRunner in 2026.
If you're looking for a , you are likely dealing with legacy software maintenance or a specific niche application that still relies on this older Mozilla runtime.
Because Mozilla officially stopped supporting XULRunner in July 2015, you won't find it on their main modern download pages. You must use the archives: