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SignalDesk AI – Crossref DOI Lookup
x402
SignalDesk AI – Crossref DOI Lookup is a paid API for AI agents from x402-agent.kariguetoazul.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-12).
Fetches structured bibliographic metadata for a scholarly article given its DOI, sourced from the Crossref API
Price / call$0.003
Success—
StatusUnknown
How this service works
Evidence-backed autonomous AI jobs and paid data tools. Queue/D1/cron run outside the chat; free quotas and bounded execution apply.
Output
A JSON object containing the DOI, canonical URL, article type, publication year, title, list of authors (given and family names), citation count, publisher name, license details (URL, start date, content version), and source provenance metadata including when the record was fetched and its expiry.
Example use cases
Verify paper authorship from a citation
“I found a citation that mentions DOI 10.1016/j.cell.2021.05.001 — can you look it up and tell me who the authors are, when it was published, and what journal it appeared in?”
Check citation count for a research article
“How many times has the paper with DOI 10.1126/science.1251186 been cited? Also grab the title and publisher while you're at it.”
Retrieve license info before reproducing a figure
“I want to reuse a figure from the paper DOI 10.1038/nature12373 — can you look up its license details and tell me if there are any restrictions on reuse?”
Technical details
Endpoint
GEThttps://x402-agent.kariguetoazul.workers.dev/api/research/crossref-doi?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need structured, evidence-backed bibliographic metadata for a known DOI — especially when you need citation counts, license terms, author lists, or publisher details from Crossref specifically. Prefer this over a generic web search when you need machine-readable, normalized scholarly metadata rather than a human-readable abstract page.
Side effects
- Invalid or malformed DOI format (must match pattern ^10\.[0-9]{4,9}/\S+$) returns a validation error
- DOI not found in Crossref registry returns a 404 or empty result
- Crossref API upstream unavailability causes a timeout or 503
- Payment not completed (x402 payment required) results in a 402 response before data is returned
- Rate limit or quota exhaustion on free tier blocks requests
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"doi": "10.1038/nphys1170",
"url": "https://doi.org/10.1038/nphys1170",
"type": "journal-article",
"year": 2009,
"title": "Measured measurement",
"source": {
"provider": "Crossref metadata",
"expires_at": "2026-10-03T09:44:49.169Z",
"fetched_at": "2026-10-02T09:44:49.169Z",
"source_url": "https://api.crossref.org/works/10.1038%2Fnphys1170",
"transformed": true
},
"authors": [
{
"given": "Markus",
"family": "Aspelmeyer"
}
],
"cited_by": 11,
"licenses": [
{
"URL": "http://www.springer.com/tdm",
"start": {
"date-time": "2009-01-01T00:00:00Z",
"timestamp": 1230768000000,
"date-parts": [
[
2009,
1,
1
]
]
},
"delay-in-days": 0,
"content-version": "tdm"
}
],
"publisher": "Springer Science and Business Media LLC"
}
}Tags
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