What is API for Crossref.org DOI Metadata?

API for Crossref.org DOI Metadata is also called Crossref Unified Resource API, which allows anybody to search and retrieve content information associated with DOIs registered in Crossref.org.

As of April 9, 2020, Crossref.org database has about 112.5 million DOI records.

Technical information on Crossref.org API:

Base URL: https://api.crossref.org
Resources: 
  /works - for journal articles, conference proceedings, books, components, etc
  /funders - for funders in the Funder Registry
  /members - for Crossref members (mostly publishers)
  /types - for work types
  /licenses - for licenses applied to works in Crossref metadata
  /journals - for journals in the Crossref database

Here is an example of Crossref.org API request and response:

fyicenter$ curl https://api.crossref.org/works/10.1037/0003-066X.59.1.29/agency

{
  status: "ok",
  message-type: "work-agency",
  message-version: "1.0.0",
  message: {
    DOI: "10.1037/0003-066x.59.1.29",
    agency: {
      id: "crossref",
      label: "Crossref"
    }
  }
}

For more information, see Crossref Unified Resource API Document.

⇒ crossref.org API - /types for DOI Types

⇐ crossref.org - DOI Metadata Lookup

⇑ Crossref.org DOI Database

⇑⇑ DOI - Frequently Asked Questions