I'll give this an extra star because it does apparently work for many others, but not for me. I've ran into research papers in Nature, Astronomy and Astrophysics, The Astrophysical Journal, and many others that were behind a paywall, where the green unlocked icon came up, indicating it had located an open access version. However, hitting it just opens the webpage I'm on again in a new tab with another green icon that does the same. If this worked as intended for me, it would save countless hours of searching repositories like arxiv myself. Bummer.

As it stands, the one very useful function it serves, is if the icon comes up grey and locked, I know not to waste my time searching for an open access version elsewhere, or asking AI to scour the web for something that doesn't exist (AI deep research always confirms this).

Note: After reading through these comments, there seems to be a great deal of confusion about what Unpaywall does. First off, this is NOT for news and online magazine articles. For that you want the RemovePaywalls.com extension. Unpaywall is for scholarly articles, such as academic research papers. Also, Unpaywall doesn't "Break through" the paywall and open the research paper up on the publisher's site. It searches the web for a site where you can read it legally without paying, so you don't have to do it yourself. If the icon comes up grey and locked, it doesn't mean it's not working. It means it couldn't find an open copy in any of the usual places. Last, if it's not working for you, try disabling ad blockers and other extensions, since they can interfere with all sorts of things.

Perfect add-on

really useful tool. The best!

Does what it's supposed to do. Awesome add-on, as education should be free!

Doesn't work, can't click the icon.

jquery in this extension differs from the one of the same version on the jquery website, specifically code.jquery.com/jquery-3.1.1.min.js

Amazing!