Greatest Firefox extension of all time, as far as I'm concerned. I keep a Febe backup of my Firefox settings on a USB stick on my keychain. I need a URL, or an extension, or restore my entire profile to the PC I'm on at that moment? Sure! Just takes a few minutes. It's much more secure than uploading everything to the cloud like Chrome does.
Because the new Firefox broke Febe, I keep a copy of the Firefox v56 installer on the keychain now as well. :D