Please don't misuse reviews and ratings for tech support. If the addon really didn't work, nobody would be giving it 5 stars to this day and it would probably get delisted. You can't give me any information I need through here, nor can I give you any meaningful help, and ratings like this are simply not a fair lasting assessment or based on anything solid. Comments like this have been left dozens of times and it's always just been the person's pc somehow, not the addon.

I just installed it in my own firefox, went to xkcd.com, and double-clicked the frontpage comic. It faded out and in (indicating download) and the image appeared in my downloads as expected.

Please know that this addon and its successor userscript simply can't be guaranteed to work on all sites because overlays and other structural details can prevent image detection. In my experience it works 99% of the time, just not on a few usual culprit websites because of their particular GUI.

If it doesn't work on xkcd for example, even after restarting firefox just to make sure, please get in touch via the listed support email. That's the only way we can seriously work on issues (since the code repo is archived and you can't post tickets there).

As mentioned many times before (I should add this to the FAQ part), it depends on the website, this observation is not global. Many servers provide filename extensions one way or another, but e.g. twitter doesn't in any way (because websites don't need to) and my addon can't just take a wild guess as it. There will be an extension if the extension is communicated by the server as per standards. What a blown-out-of-proportion thing to give a permanent 1 star for anyway, as if that's all there is to it and as if it's any addon's fault a server decides not to expose extensions. Stupid "reviews" - more like baseless whines - like this are why I'm done developing for the public anyway.

Sorry, they probably detect hotlinking (i.e. direct downloading) specifically to stop addons like this. Thank you for giving a reasonable rating to a functioning product, unlike all the petulant reviewers that go straight to 1 star for the silliest reasons as if it's a completely defective piece of junk.

Some websites do things to stop addons like this from working, and I can't change that. But the addon definitely works on sites that don't take such countermeasures. I use it myself in the latest firefox, as do many other happy reviewers. Don't use reviews for misplaced and false bug reports, they belong in an email with proper information like which site you're trying to use it on. Simply writing "doesn't work" is an utter waste of everyone's time and blatantly wrong.

Sorry but I'm using firefox and this addon myself, and it definitely works, as it does for other people too. There are some sites that do things that prevent addons like this from working (e.g. clickable overlays on images), you may be trying to use it on such a site. Fair enough it doesn't work then but that's no basis to say this addon never works. Please use reviews only for serious, well prepared review content.