Mozilla maintains an official archive of every version ever released. To ensure your system remains safe from malware, you should only download these older versions directly from Mozilla’s servers. 1. The Mozilla FTP Archive
Web developers often use Firefox 12-51 to ensure backward compatibility for specific enterprise clients. firefox 12-51 and 52 esr download
Firefox 52 ESR is unique because it was the last version to support several critical technologies: Mozilla maintains an official archive of every version
Look for your locale (e.g., en-US for American English). firefox 12-51 and 52 esr download
Playing legacy Flash or Shockwave games that no longer run in modern "Evergreen" browsers.
It was the final version of Firefox compatible with these operating systems.
Versions 12 through 51 contain known vulnerabilities. Use them only in "sandboxed" environments or for specific offline tasks.