Crossref — DOI Metadata

Crossref is the largest DOI (Digital Object Identifier) registration agency. Every DOI you've seen in an academic citation goes through them. Their API exposes structured metadata for ~150M+ scholarly works: titles, authors, ORCIDs, abstracts where available, references, citation graphs. Free, no auth required.

Part of Pipeworx — an MCP gateway connecting AI agents to 1394+ live data sources.

Why this matters for AI agents

Where Semantic Scholar is search-focused, Crossref is the authoritative source for DOI metadata. If you have a DOI and need its canonical metadata, Crossref is the answer. Citation networks are also more complete here than in many discipline-specific databases.

Common flows:

• DOI → metadata. crossref_get_work({doi: "10.48550/arXiv.1706.03762"}) → title, authors, journal, year, citations.

• Author DOIs. Find a researcher's published works by ORCID or name.

• Citation graph. A paper's references and which papers cite it (where reported).

For free-text academic search, prefer Semantic Scholar — Crossref's search is more limited.

Citable URI: pipeworx://crossref/work/{doi}.

Related MCP server: crossref-mcp

Auth

Public, free. Crossref has a "polite pool" giving priority to clients that identify themselves via User-Agent. Pipeworx forwards pipeworx-mcp/1.0 (https://pipeworx.io) so we get polite-pool treatment by default.

What's in a Crossref record

Common pitfalls

• Reference-list completeness. Some publishers send their full reference list to Crossref; others don't. A paper with 0 references in Crossref may have 50 in print. For exhaustive citation graphs, cross-reference with Semantic Scholar.

• Errata and retractions. Crossref tracks "scholix" links between original and retraction notices. Always check the relation field for is-retracted-by before citing.

• Author ORCID coverage. ORCID adoption has grown but isn't universal. Older papers and small-publisher works often lack ORCIDs. Don't rely on ORCID-based deduplication for full coverage.

• DOI normalization. Different sources format DOIs slightly differently: 10.1234/xyz, https://doi.org/10.1234/xyz, doi:10.1234/xyz. Crossref accepts the bare form. Strip prefixes before passing to the API.

• Books and chapters. Crossref covers books and chapters as well as articles. The type field tells you which (journal-article, book-chapter, proceedings-article, etc.). For systematic literature reviews, type filtering matters.

• Pre-prints. Some pre-print servers register DOIs through Crossref (arXiv, bioRxiv). The same content may have multiple DOIs (pre-print + accepted version). Track via relation field.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "crossref": {
      "url": "https://gateway.pipeworx.io/crossref/mcp"
    }
  }
}

Or connect to the full Pipeworx gateway for access to all 1394+ data sources:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English:

ask_pipeworx({ question: "your question about Crossref data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides

• pipeworx.io

License

MIT