Is Unpaywall safe?

Unpaywall reads DOIs from pages you visit and transmits them to api.oadoi.org to look up open-access versions.

On every page load, the extension scans the page HTML for Digital Object Identifiers (DOIs) in meta tags and page source. When a DOI is found, it sends a request to api.oadoi.org identifying the scholarly article being viewed. This allows the extension to surface free, legal copies of research papers, but also means the operator receives a record of which articles the user reads.