firebug - What are the alternatives to the Firefox Developer Tools?

Question

Since last few updates of Firefox our beloved Firebug is integrated into the Firefox Developer Tools and a lot of people including me don't like what happened to Firebug.

The built-in developer tools have a very ugly menu system and messed up usability.

So, what are the alternatives to the Firefox Developer Tools? Is there a tool with the same usability as Firebug?

Answer 1

Alternatives are:

1. Turn off multi-process Firefox. (Though that's only a temporary solution and doesn't bring back all functionality of Firebug. E.g. the Script panel is broken in current versions of Firefox.)
2. Install an old version of Firefox where Firebug still works and disable updates. (Also only a temporary solution, because you'll miss (security) bug fixes and new features.)
3. Wait until the gaps between Firebug and the Firefox DevTools are fixed. (Or even help them fixing them.)
4. Switch to another browser and use its developer tools.
5. Rework Firebug to make it compatible with multi-process Firefox (which is the main reason for the integration into the DevTools). Update: Starting with Firefox 57 only WebExtensions will be supported, meaning extensions work cross-browser and are more secure, but they also have limited APIs. So, a reworked Firebug would not have all the features the original Firebug had.