Crossref Has a Free API — Look Up Any DOI and Get Full Metadata (No Key)

#python #api #research #tutorial

Every research paper has a DOI. But did you know you can resolve ANY DOI to get full metadata through a free API?

Crossref manages 150M+ DOIs and provides a completely free, no-key API to query them all.

What Is Crossref?

Crossref is the DOI registration agency for scholarly content. Their API lets you:

Resolve any DOI to full metadata
Search across 150M+ works
Get citation counts and funding info
No API key needed

Quick Start

import requests

doi = "10.1038/s41586-021-03819-2"
response = requests.get(f"https://api.crossref.org/works/{doi}")
work = response.json()["message"]

print(f"Title: {work['title'][0]}")
print(f"Journal: {work['container-title'][0]}")
print(f"Citations: {work['is-referenced-by-count']}")
print(f"Authors: {len(work['author'])} authors")

Search Papers by Topic

response = requests.get("https://api.crossref.org/works", params={
    "query": "CRISPR gene editing",
    "rows": 5,
    "sort": "is-referenced-by-count",
    "order": "desc",
    "mailto": "your@email.com"
})

for work in response.json()["message"]["items"]:
    title = work["title"][0] if work.get("title") else "No title"
    cites = work.get("is-referenced-by-count", 0)
    print(f"{title} ({cites:,} citations)")

Find Funding Information

doi = "10.1038/s41586-021-03819-2"
response = requests.get(f"https://api.crossref.org/works/{doi}")
work = response.json()["message"]

for funder in work.get("funder", []):
    print(f"Funder: {funder.get('name', 'Unknown')}")
    print(f"  Awards: {', '.join(funder.get('award', ['N/A']))}")