Unpaywall is a browser extension for Chrome and Firefox that detects when you’re looking at a paywalled journal article and adds a small color-coded tab to the right side of the page.
A green tab with an image of an unlocked lock means that Unpaywall can connect you to an OA version of the article. Want the article? Just click the green tab, and it’ll take you to the OA version. A simple, single click, and you’re there.
A grey tab with an image of a locked lock means that Unpaywall can’t connect you to an OA copy. Either there is no legal OA version, or, if there is, Unpaywall isn’t aware of it (i.e., if none of its data sources include it).
Once Unpaywall is installed, the tab automatically appears when you’re on a publisher’s site — no need to do anything to check the status of a given article. It’s there when you need it and easy to ignore when you don’t.
Credit: CC BY NC SA from CUNY Graduate Center Library