Firefox ESR 68.5.0 (see security notes and downloads) brings the fixes to the Extended Support Release family for OS X 10.9 or later, Linux, or Windows. A Firefox FTP server includes all the various versions for downloading.
Firefox Quantum Developer Edition is an alternate version for desktop systems that incorporates tools such as editors, debuggers and responsive design views. Firefox Quantum for Enterprise is a version that lets people set up policies (e.g. proxy, restrict features) with Group Policy on Windows and a JSON file on Mac and Linux.
Firefox for iOS 22.0 is a free mobile version for iOS 11 and up, with automatic search suggestions, a private browsing mode, tracking protection and Siri Shortcut support for iOS 12.