Clear history cookies and website settings, then restart Firefox, add-on settings are been deleted.

Great extension that really speeds up some site, such as Amazon. I hope another developer will continue work on it.

Has made many sites with annoying pop-ups and sound usable again, e.g. Medium

Perfect. Using it along with *a lot* of privacy addons and haven't run into a single issue.

Congratulations to the author, and thank you for this add-on!

I am using WebApiManager along with UMatrix... what a nice complement! With this two adds-on is hard to need other ad-blockers, anti-tracking, cookie managers etc.
It might be great a kind of fusion of this two great adds-on. First, due to potential gains in performance (less system resources, faster blocking etc). And second, because it will be easier to use WebApiManager in a matrix layout (like UMatrix). It would be perfect to have a matrix showing just active APIs for each webpage, allowing granular control for blocking/unblocking active APIs per webpage.

For now, please I just request from the author, to add in the dashboard an "enable/disable switch", or a kind of "temporary rules switch".
And from us users community, it will be nice in the future to see a shared collection of customized settings of blocked APIs, for the most important websites (avoiding breaking pages and its functions).

Thanks again to the author!

PS: I read the articles attached by the author, found them very interesting, and recommend the reading in order to better understand the benefits (privacy, security, performance etc) of this great add-on. Quoting:
"We evaluated our extension with two hardened browser configurations, and found that blocking 15 of the 74 standards avoids 52.0% of code paths related to previous CVEs, and 50.0% of implementation code identified by our metric, without affecting the functionality of 94.7% of measured websites."

gets better with every release. have you considered adding options to block telemetry etc? theres a ton of info here https://github.com/ghacksuserjs/ghacks-user.js/

Seems like the perfect companion to NoScript. I used aggressive but after a little browsing and watching YouTube so far I've had to make a few adjustments:

uncheck CSSOM View Module
uncheck File API
uncheck Fullscreen API
uncheck HTML: Web Storage
uncheck Media Source Extensions
uncheck Selection API

I went ahead and checked these two because I don't need them:
check Service Workers
check Vibration API

it'd be nice to have my prefs sync or have a backup method because I know I'll forget my settings.

A Must for the anti-tracking tool kit.
But: It needs a lot of reading and understanding to use all the features efficiently without too many side effects.