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Research Paper & DOI Lookup (Crossref)
x402
Research Paper & DOI Lookup (Crossref) is a paid API for AI agents from paper-lookup-production-56b0.up.railway.app, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-30).
Search or resolve scholarly publications using Crossref's 150M+ record database, returning metadata including authors, journal, citation count, and full-text links.
Price / call$0.005
Success—
StatusUnknown
How this service works
Scholarly works metadata from Crossref (150M+ records): resolve a DOI, or search by keywords, author or title with year and type filters. Returns title, authors with ORCID, journal or publisher, publication date, type, ISSN/ISBN, citation count, references count, licence and full-text links, funders. Abstracts are excluded. Use when an agent must verify a citation or DOI, find papers on a topic, or get a paper's authors, journal, date, citation count and links.
Output
Returns a JSON object with status, total result count, and an array of paper records each containing: DOI, canonical URL, publication type, title, authors (with ORCID where available), citation count, container (journal/publisher name), and publication date. Also includes legal/terms links and a use_when guidance field.
Example use cases
Citation verification for a report
“I need to verify this citation before I submit my paper — can you confirm the authors, journal, and publication date for DOI 10.1016/j.watres.2018.05.060 and check how many times it's been cited?”
Literature search on a research topic
“Find me up to 10 journal articles about CRISPR gene editing published between 2019 and 2023 — I need the titles, authors, and citation counts.”
Author publication lookup
“What papers has Jennifer Doudna published? Search for her as an author and give me a list with titles, journals, and publication dates.”
Technical details
Endpoint
GEThttps://paper-lookup-production-56b0.up.railway.app/v1/papers/search?utm_source=zero.xyzWhen to prefer
Choose this endpoint when an agent needs to verify, look up, or search scholarly publications using Crossref's authoritative 150M+ record database. Ideal for DOI resolution, citation verification, author searches, and topic-based literature discovery with year and type filters. Prefer over Google Scholar scraping or PubMed when broad cross-domain coverage and structured metadata (ORCID, funders, licences, citation counts) are required.
Side effects
- DOI not found in Crossref — returns empty results or error status
- Query returns zero results if keywords are too specific or misspelled
- Rate limiting or payment failure returns 402 Payment Required
- Invalid DOI format may return an error or empty match
- Some records may lack citation counts, ORCID, or full-text links if not registered with Crossref
- Abstracts are intentionally excluded from all results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"legal": {
"terms": "https://paper-lookup-production-56b0.up.railway.app/terms",
"privacy": "https://paper-lookup-production-56b0.up.railway.app/privacy"
},
"total": 28674,
"status": "ok",
"results": [
{
"doi": "10.1016/j.watres.2018.05.060",
"url": "https://doi.org/10.1016/j.watres.2018.05.060",
"type": "journal-article",
"title": "Microplastics in drinking water ...",
"authors": [
{
"name": "A. Author",
"orcid": null
}
],
"cited_by": 512,
"container": "Water Research",
"published": "2018-09-01"
}
],
"use_when": "Use when an agent must verify a citation or DOI, find papers on a topic, or get a paper's authors, journal, date, citation count and links."
}
}Tags
x402
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