To people who are saying this doesn't work: once you are on the 'Manage Your Extensions' page, you just need to click the little gear button near the top, and then click 'manage extension shortcuts' at the bottom of the pop-up menu. The description should perhaps be updated, but the add-on works. Make sure what you want is on the list though; and this add-on can't override existing shortcuts.

Sadly, most of the reviews saying that Shortkeys isn't working for them, are prime examples of people who haven't read (or don't understand) the extension's description as well as its documentation (on GitHub).
Some of them apparently don't understand how WebExtensions work.

If you're unsure something is working as intended and/or if you're trying to get help in that respect, you should use GitHub to file a ticket and not try to pressure them with these unwarranted reviews.

The devs haven't been noticeably active in the past couple of months, so I seriously hope that this extension will continue to work as long as possible.

Best, i save my backspace again, fuck you firefox!

Works exactly how it is described in the description, all the negative reviews are people who didn't actually read what this extension can do and what its limitations are.

Thank you! Very useful extension. Now I can disable/change meaningless hotkeys.

Thanks for helping me disable all the idiotic built-in shortcuts like Ctrl+Shift+C that I keep triggering by muscle memory from other apps.

Works very well. I can finally disable ctrl-shift-C .....

Must-have add-on. Thanks!

Probably one of the most under-appreciated (by public rating) Extensions on the entire Firefox Add-ons site. This Extension is one of the most powerful Add-ons any Firefox customization hacker could hope for. Unfortunately for them the source of that power is also the likely cause for the low rating, using its best features (hotkey initiated custom JS) requires extensive developer knowledge and testing time. Couple that with the incredibly unfriendly tiny UI Window (with hidden Save Button) and it is no wonder new users find difficulty & rate it low.

It seems like the "Run custom JS" feature is treated as an afterthought, but I wish the devs would extend it, for example: JQuery support; custom CSS/HTML/DOM; pass dynamic parameters to commands (ie: use JS to find a particular anchor or img.src then go to it in a new tab); Download/Save a resource by URL (option to bypass save-as dialog); would be awesome to be able to call a particular context menu item of an object on the page;

Currently I am using multiple add-ons to do most of what I need, but as I mentioned even without those dream features this is by far one of my favorite extensions available. HIGHLY RECOMMEND for those that know how to code.

let me try

Simple and awesome. Exactly what I needed.
Thank you! Good work.

This extension has a few downsides in its UI, but for its built-in shortcut keys (manageable through browser shortcuts), they work like a charm.

A shame it seems to no longer be maintained.