I work as a web developer on the OutSystems platform and use FireFox all day long for testing, inspecting and debugging HTML, CSS and Javascript code. In my opinion is the best web browser out there :)
Until I knew the multi-account containers extension, I had to constantly login and logout while testing web apps under several profiles. Now, with this extension, I can be logged in under several usernames (each with its own session) on the same browser window and it has made my work soooo much easier!
Thank you very much for your fantastic work on this extension!!!