Unpaywall

Unpaywall is a free online tool that helps you find legal versions of research articles and academic papers. When you come across a paywalled article behind a publisher’s site, Unpaywall searches for an authorized, free copy available openly online. It scans repositories and websites that store open-access versions, providing a green "free" badge if available. This makes it easier for students, researchers, and the public to access scholarly information without cost, promoting wider sharing of knowledge and reducing barriers to scientific research.