The Firefox browser is open source, provides Enhanced Tracking Protection and soon will support DNS over HTTPS - all part of our longstanding commitment to data protection. Firefox ESR does not come with the latest features but it has the latest security and stability fixes. Extended release support version of Firefox without the bleeding edgeįirefox Extended Support Release (ESR) is an official version of Firefox developed for large organizations like universities and businesses that need to set up and maintain Firefox on a large scale.