Developer Edition enables a number of features not currently available for regular Firefox. The two major ones are build time features which can't be enabled in other releases (besides Nightly). One build feature is Unsigned Add-ons, which allows for add-on development where it isn't possible otherwise. The other is Async JavaScript callstacks which are very useful to capture but tend to slow down regular browsing otherwise. Besides build features there a lot of prefs we turn on to make development easier. If you try using Chrome or Firefox release with DevTools you will need to do something extra to be able to "paste into the console" (something that prevents people on facebook from owning themselves) and that guard isn't on by default in Developer Edition. [I'm the Product Manger for Firefox DevTools]

> Unsigned Add-ons, which allows for add-on development where it isn't possible otherwise

It is possible, you've just chosen to disallow it.

To be clear: the Firefox team took deliberate steps to make sure that add-ons can't be tested or developed in the stock builds of Firefox downloaded from Mozilla.

Don't think you're right. You can use FDE for add-ons development, just like parent said.

See your sibling below: > Unsigned addons cannot be enabled on beta or release. That was only available for a limited time. Now they can only be enabled on alpha (aka developer), nightly, or special unbranded builds.

Please read and understand the entire comment chain you're replying to. I'm well aware that you can use Firefox Developer Edition to develop add-ons. (I'm the one who first mentioned it!)

AFAIK this isn't correct. FDE has some about:config flags set to different defaults than the Stable release, which could mean that a user of Stable might need to flip a switch to allow loading unsigned addons, but there's nothing stopping you from doing so (and addons aren't exactly part of the web platform).

Unsigned addons cannot be enabled on beta or release. That was only available for a limited time. Now they can only be enabled on alpha (aka developer), nightly, or special unbranded builds.

You can make a userscript without any of that hassle, though.

I stand corrected!