CrossRef is an independent membership association, founded and directed by publishers. CrossRef’s mandate is to connect users to primary research content, by enabling publishers to do collectively what they can’t do individually. CrossRef is also the official DOI registration agency for scholarly and professional publications. It operates a cross-publisher citation linking system that allows a researcher to click on a reference citation on one publisher’s platform and link directly to the cited content on another publisher’s platform, subject to the target publisher’s access control practices. CrossRef’s citation-linking network today covers millions of articles and other content items from several hundred scholarly and professional publishers.