Unpaywall

About Unpaywall

Unpaywall finds a legal free copy of a paper using its title or DOI, with an optional author name to distinguish similar titles.

Get free version returns the best available link and other copies; if no free copy is indexed, copy links are null.

Built by Fous from unpaywall.org and crossref.org and checked automatically; it last passed a check on Sep 29, 2026. Fous is not affiliated with Unpaywall.

Actions

{
  "doi": "10.1038/35057062",
  "host": "Springer Science and Business Media LLC",
  "year": 2001,
  "title": "Initial sequencing and analysis of the human genome",
  "journal": "Nature",
  "licence": "Public domain",
  "version": "published",
  "free_to_read": "yes",
  "landing_page": "https://doi.org/10.1038/35057062",
  "best_free_link": "https://www.nature.com/articles/35057062.pdf",
  "other_free_copies": [
    {
      "host": "University of Michigan",
      "link": "https://hdl.handle.net/2027.42/62798",
      "landing_page": "https://hdl.handle.net/2027.42/62798"
    }
  ]
}

For developers

Run this workflow from your own code. In Studio, turn on Developer mode and create an API key.

# First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
: "${FOUS_API_KEY:?Set FOUS_API_KEY before running this example}"

curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 120 \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@unpaywall",
  "visibility": "public",
  "operation": "get_free_version",
  "version": 1,
  "input": {
    "paper": "10.1038/35057062"
  },
  "response": {
    "format": "json"
  }
}'

What you can do with it

• Find free versions of papers by title or DOI
• Distinguish papers with similar titles using an author name
• Compare available copies by host and landing page
• Check a paper’s journal, year, licence, and version

Questions

Related workflows

• Semantic ScholarSemantic Scholar returns paper and citation search, paper abstracts, summaries, authors and influence, plus author metrics and up to 10 top-cited papers; dates, summaries, PDFs and affiliation matches may be unavailable.
• OpenAlexOpenAlex is an open catalog of scholarly research and connections, offering ranked papers and institution research summaries with annual output, leading topics, and coauthors.
• arXivarXiv returns up to 100 matching research preprints or individual paper details, and newly announced subject papers in announcement order; announcement dates may differ from today, and replacements are excluded.
• CrossrefFind scholarly works and format citations from their registered metadata.
• Google ScholarGoogle Scholar provides papers, citing papers, ready-made citations and researcher profiles with metrics and up to 20 top-cited papers; public access may be temporarily limited.
• PubMedPubMed searches medical and life-science articles by topic and retrieves one article’s abstract and publication details; abstracts and free full-text links may be unavailable.
• AP NewsAP News provides reporting, up to 50 public-page headlines, searchable articles visible in its search, and full text when accessible.
• OverDriveFind ebooks and audiobooks at public libraries.

All Science workflowsBrowse all workflows