Article Access
Paste a DOI, PubMed ID, or citation and it finds the legitimate ways to read the full paper.
Problem
Research papers often sit behind paywalls, and finding a free or library copy means checking several sites by hand.
Solution
It looks for an open-access copy first, then your library's proxy link, then the publisher, in that order, and never claims access it can't find. On the first run you set your Unpaywall email and library proxy prefix once.