Header Inject

okayish. adds the header to ALL requests. you are not able to specidy url filters or something.

Simple and just works

Extremely simple, but it works like a charm! It's open source, too. Just make sure that when you're using it that you pay attention to main enable/disable button at the top and also in the right-click menu (otherwise it may seem like it's not working).

Doesn't work. Tried to inject a header for authentication on a development environment site, it did no such thing. (Flicked the unclear enabled/disabled button too, no change.) The UI to add a header annoyingly disappears when trying to paste things into it.