A New Browser Plug-In Lets You Access Millions of Scientific Papers for Free

"Unlike similar services that rely on means like automated web scraping, Unpaywall’s method of getting full-text access to scientific journals is totally legal. It scans a database of more than 90 million digital object identifiers (DOIs) for copies of papers that the researchers themselves have uploaded, whether on some pre-press servers or university websites. Unpaywall is also completely secure, as it doesn’t ask you for any personal information.

Best of all, to use the service, you just need to install the plug-in on your Chrome or Firefox desktop browser. A little lock symbol will appear every time you visit a journal article’s landing page. If the lock is green, you have access to a full-text copy of the article. A gold lock means an article already has open license access from the publisher."