scholarly-metadata
DataCite REST API
The DOI registry for research outputs beyond journal articles — datasets, software, and preprints — covering tens of millions of DOIs. Records can be looked up or searched through a free API with no key required. It is the complement to Crossref when the object you are tracing is a dataset or a piece of research software rather than a paper.
Academic papers API
Why it’s useful & how it works
No key for reads. Complements Crossref (datasets/software). Works both ways.
What’s inside
Tens of millions of DOIs.
API access
https://api.datacite.org/dois/ <doi> ; query ?query=...
Access
Programmatic API access (a key may be required — see the API tag).