Free APIKnowledgeNo keyOfficial
Crossref REST API
Authoritative metadata and DOIs for 165M+ scholarly records, no key
Crossref is the DOI registration agency for scholarly publishing; its REST API exposes deposited metadata for 165M+ journal articles, books, datasets and preprints, including titles, authors, references, funders, licenses and ORCID/ROR IDs. It is open with no key; adding your email unlocks the faster, more stable polite pool.
Free tier
Free, no key. Optional Metadata Plus tier (paid) for guaranteed throughputRate limits
Not published as fixed numbers; the public and polite pool limits were revised on 1 Dec 2025. The polite pool (with mailto) gets higher, more stable limits than the anonymous poolAuth
No keyBase URL
https://api.crossref.orgWhat you'd build with it
- Resolve a DOI to clean citation metadata for a reference manager
- Validate and de-duplicate bibliographies in a research automation
- Search the scholarly record by funder, license or publication date
- Pull reference lists to build a local citation graph
Key endpoints
- GET
/works/{doi}Full metadata for a single DOI - GET
/works?query={q}Search works by free text, with facets and filters - GET
/journals/{issn}/worksAll works in a journal by ISSN - GET
/funders?query={name}Look up funder registry records
Members
Members get the runnable recipe
Sign in free to copy the example request, see a sample response, and read the gotchas.
Tags
knowledgeresearchdoicitationsreference