NCBI Entrez E-utilities API
The Entrez Programming Utilities (E-utilities) are the public API to the NCBI Entrez system, providing access to over 38 Entrez databases including PubMed, GenBank (Nuccore), Gene, Taxonomy, and Protein. Nine server-side programs support text search, record retrieval, batch download, database linking, spelling correction, and citation matching. Requests can be authenticated with an API key to raise rate limits from 3 to 10 requests per second.