CrossCheck is a CrossRef initiative to provide tools for the prevention of scholarly and professional plagiarism. There are two elements to CrossCheck: the database and the originality (plagiarism) detection tool (iThenticate software provided by iParadigm):
The database contains indexed published content from CrossCheck members. (For a full list of members see: http://www.crossref.org/crosscheck_members.html)
The originality detection tool iThenticate checks authored works against the database content. This is done through a web-based tool by uploading a document and running a similarity check against the database and (optionally) the Internet.