Download Firefox 12-51 52 Esr _best_ May 2026

Downloading and using older versions of Firefox like or versions 12 through 51

John decided to download Firefox 52 ESR, thinking it would be the best option for him. He clicked on the download link and waited for the installation file to finish downloading.

Firefox ESR 52.0esr, See All New Features, Updates and Fixes Download Firefox 12-51 52 Esr

For organizations with legacy enterprise software reliant on Java applets, or for libraries maintaining public access terminals that require specific legacy drivers, Firefox 52 ESR is the only viable bridge to the modern web. Unlike the standard release channel, the ESR channel received security updates for nearly a year, meaning a downloaded copy of 52.9.0 ESR is stable, relatively secure (by 2018 standards), and functional on older operating systems like Windows XP and Vista that modern browsers have long abandoned.

Legacy Releases (v12 – v51): You can browse the full directory of every version ever released on the Mozilla FTP Archive. Key Version Differences Version Range Key Features / Support v12 – v51 Downloading and using older versions of Firefox like

Step 2: Locate Your Version

In the directory, you will see a list of folders. Look for:

Select your operating system (e.g., win32, win64, mac, or linux-x86_64). If the archive provides SHA256/SHA1 checksums or PGP

Disable Auto-Updates: If you need to stay on an old version, go to Settings > General > Firefox Updates and select "Check for updates but let you choose to install them" to prevent it from jumping to the latest version. ⚠️ Security Warning