Reverse DOI lookup using the Crossref API · INTACT

"In principle, knowledge of an article title allows for rather easy retrival of the associated DOI: It usually involves copy-pasting the string into a search engine, following the first link to a landing page or full text PDF and looking for the DOI there. While this is doable for a small number of data points, it quickly becomes infeasible for larger sets of data, and 3000 articles is clearly too much to look up manually."