Sorry, there's currently no way to add manual rules. This is something I'd really like to add in the future (see https://github.com/qsniyg/maxurl/issues/41), but currently there are a few technical problems with implementing this for the moment (see the linked issue for a bit more detail on why).

If you want to request a new site to be added to the script, feel free to use any of the contact links listed at the bottom of the script's description, whichever you're most comfortable with. I'm more than happy to add any new website to the script, and if I'm online, I usually add them within minutes of being notified :)

If you'd rather add it to the script yourself (note that this will require sideloading the addon), I've written a bit of a guide here: https://github.com/qsniyg/maxurl/blob/master/CONTRIBUTING.md#websiterule-contributions. In your case, a rule like this should work: if (domain === "subdomain.your-website.com") return src.replace(/(\/[0-9]+-)small(\.[^/.]+)(?:[?#].*)?$/, "$1original$2");

By the way, while the github issue hasn't seen much activity for a while, this does not mean it's been forgotten or ignored, the script is already getting restructured in many areas, which will facilitate the implementation of this. It's just that it is pretty a massive project (currently requires rewriting >70,000 lines of source code - much of which will be automatically handled, but even that requires a very significant amount of work).

Glad to know it's helpful!!
I should note however that this does not replace using a reverse image search engine, but rather complements using one. It'll find larger versions stored within the website itself (either through URL patterns or API calls), which are sometimes larger than what reverse image search engines can find (unless they crawl a page that contains the original image), but if the original image uploaded on the site is smaller than what's available on another site (e.g. an image reuploaded to a blog), it won't be able find that version.

(Sorry for the late reply, for some reason I hadn't been notified)

>it's just that I'm hindered a bit by how to popup-on-hover doesn't disappear when we leave the thumbnail beneath
If you set "Popup position" -> "Beside Cursor" (as you wrote), and "Close when leaving thumbnail" (which should be the default), it should work, at least it does for me on Reddit... would you mind opening a github issue (link is on the addon page) for which site you're using that doesn't work (and maybe your settings as well, if you click "Export" at the top)? I'd like to fix this if possible :)

EDIT: I think I understand what you meant now. Previously, the behavior was to close the popup if the cursor was out of both the popup, and the thumbnail. In 0.12.5, you can now customize this to be only the thumbnail if you prefer (through "Close when leaving" -> Thumbnail)

>The Options page could be visually improved imo
I completely agree, this is one of my next priorities. Even I get lost in them, so that's definitely not a good sign haha. Thanks for the suggestions on how to do it, I'll keep them in mind! (tracked here: https://github.com/qsniyg/maxurl/issues/91)

EDIT: As of 0.12.16, I've implemented the frames feature you mentioned, and it also supports splitting categories into tabs. Thanks for the idea!

>And respecting the "dark themes" of firefox too would be awesome
Good idea! I've tracked it here: https://github.com/qsniyg/maxurl/issues/189.

EDIT: It's in 0.12.3 now, if you set "Dark mode" manually in preferences. Currently for whatever reason, detecting dark mode doesn't work on my system so I can't yet add support for automatic detection.

>oh, also an entry in the context menu for blacklisting an image
I've tracked it here: https://github.com/qsniyg/maxurl/issues/127, it might take a bit longer to implement though, as a new UI would have to be made for it. But I agree, it's quite important.

>could you improve instagram support for posts that have more than 1 image/media in it
Yes, that's also something I've been thinking of working on soon. I'll try to do it in the next release if possible :) (tracked here: https://github.com/qsniyg/maxurl/issues/50).

EDIT: It's in 0.12.3, if you enable "Use albums for Instagram post thumbnails".

>Thank you for making it, improving it so much over time, and for making it open source
You're very welcome, and thanks for taking the time to write that! :)