Crossref / One work's full metadata by DOI

Full Crossref record for one DOI: title, authors with ORCID and affiliations, journal, volume, issue, pages, publisher, dates (published, issued, created), type, ISSN/ISBN, license, funders, references (when the publisher deposits them), citation count (is-referenced-by-count), links and, when deposited, the abstract (JATS XML, publisher copyright: quote it, do not republish it). Usually 5 to 50 KB. Pass the bare DOI, e.g. 10.1038/nature12373. A DOI Crossref does not hold (unknown or registered with DataCite) answers not found (404) at $0. Metadata from Crossref (crossref.org), supplied by its member publishers; bibliographic metadata is free to reuse, abstracts can carry the publisher's copyright and are left out of search results. Free, no key.