While the standard consumer version of Firefox moved on quickly, the ESR (Extended Support Release) channel for Firefox 52 was maintained for nearly a year. This gave enterprises running critical legacy web apps—such as banking portals, university registration systems, and government archives—a lifeline to update their infrastructure.
The most trusted source is the repository (look for their "Firefox Portable, Legacy Edition" or download the standard 52.0 ESR release from their archive section). Alternatively, use the official Mozilla FTP mirrors (archive.mozilla.org) to grab the installer, then manually portablize it using "PortableApps.com Launcher Generator." portable firefox 52
By 2017, Google Chrome had already dropped support for NPAPI plugins, citing security and stability concerns. Microsoft Edge (the original version) never supported them. Firefox 52 was the last major browser standing that allowed users to run legacy plugins like Java applets, Microsoft Silverlight, and ActiveX controls (via extensions). While the standard consumer version of Firefox moved
: Despite its age, it was the first version to introduce WebAssembly and CSS Grid , meaning it can still render many modern web apps reasonably well. Alternatively, use the official Mozilla FTP mirrors (archive