Mozilla Firefox ESR

Mozilla Firefox ESR is the desktop edition of Firefox’s Extended Support Release channel. Mozilla describes ESR as a browser built for enterprise use, emphasizing stability and ease of use. This cask installs the graphical Firefox.app application, rather than a command-line browser or a beta, developer, or nightly edition.

• ESR is a distinct Firefox release channel; it is not the standard Firefox, Beta, Developer Edition, or Nightly download.
• The official download page offers Firefox ESR in multiple languages. Homebrew’s cask provides language selections, with English (US) as the default.
• The installed application is placed in /Applications/Firefox.app.
• The cask conflicts with firefox, firefox@beta, and firefox@cn; these casks cannot be installed alongside it.

Install with brew install --cask firefox@esr. Open Firefox from the Applications folder to get started. The cask targets macOS. If you already have one of the conflicting Firefox casks installed, resolve that conflict before installing ESR.

Sources: Firefox ESR downloads · Homebrew cask