# SiteCheck DOI Lookup

> SiteCheck DOI Lookup is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-19).

Looks up academic paper metadata by DOI or keyword search, returning title, authors, journal, citation count, and publication details via Crossref.

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/doi?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-doi-lookup-eec5c9c1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_B0ALuuijLgqFqIvEl-NPM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sitecheck-doi-lookup-eec5c9c1
```

Example prompt: Can you look up the paper with DOI 10.1038/nature14539 and tell me the authors, journal, publication date, and how many times it's been cited?

## When to prefer this

Use this endpoint when you need to resolve a specific DOI to its full bibliographic metadata, check citation counts, or search for academic papers by keyword via Crossref. Prefer this over general web search when you need structured, reliable scholarly metadata including authors, journal, publisher, and citation count in a single call.

## Known failure modes

- DOI not found in Crossref — returns empty works array
- Invalid DOI format — may return no matches or unexpected results
- Search query too broad — returns up to 10 results but may miss the target paper
- Rate limiting or upstream Crossref API unavailability — request may fail or return stale data
- limit parameter out of range (must be 1–10) — may cause validation error

## How this service works

A DOI's bibliographic record from Crossref (title, authors, journal, publisher, date, type, citation count, license), or the best matches for a citation-style search (max 10). An unknown DOI answers 404, not charged.

## Output

A JSON object with a list of matched works, each containing the DOI, canonical URL, article type, title, author names, journal, license URL, citation count, publication date, and publisher. Also includes the data source (Crossref) and a timestamp of when the data was fetched.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "q": {
       "type": "string",
       "description": "Or a citation-style search"
      },
      "doi": {
       "type": "string",
       "description": "DOI, e.g. 10.1038/nature14539"
      },
      "limit": {
       "type": "string",
       "description": "Matches for q, 1 to 10 (default 5)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "count": 1,
  "works": [
   {
    "doi": "10.1038/nature14539",
    "url": "https://doi.org/10.1038/nature14539",
    "type": "journal-article",
    "title": "Deep learning",
    "authors": [
     "Yann LeCun",
     "Yoshua Bengio"
    ],
    "journal": "Nature",
    "license": "https://www.springer.com/tdm",
    "citations": 78302,
    "published": "2015-05-27",
    "publisher": "Springer Science and Business Media LLC"
   }
  ],
  "source": "Crossref REST API (https://api.crossref.org)",
  "checkedAt": "2026-10-14T04:49:24.968Z"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-doi-lookup-eec5c9c1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)