Is it possible to emulate older versions of Firefox

Question

Is it possible to emulate older versions of Firefox, in a similar way to Internet Explorer's Developer - Emulation mode.

Answer 1

If you want to test websites with a specific Firefox version, the only exact way is to use this version.

If you want to make the website think, you are using another version, you can use User Agent Overrider: https://addons.mozilla.org/de/firefox/addon/user-agent-overrider/