# Vextorium DOI Info Lookup

> Vextorium DOI Info Lookup is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-15).

Looks up academic paper metadata (title, authors, journal, citations, APA citation, license, etc.) by DOI

## Facts

- Endpoint: POST https://api.vextorium.com/v1/doi-info?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-doi-info-lookup-464d0946
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qQ-PEHx5Skt8dKNrBTcDJ

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 vextorium-doi-info-lookup-464d0946 -d '<json body>'
```

Example prompt: Can you look up the metadata for DOI 10.1038/nature14539? I need the title, authors, journal, year, citation count, and a formatted APA citation.

## When to prefer this

Use this endpoint when you need structured bibliographic metadata for a known DOI — especially when you need a ready-made APA citation, citation count, or author list without scraping a publisher's website. Prefer it over general web search when the DOI is already known and you want structured, machine-readable output. It is especially useful for automating citation management, research enrichment pipelines, or verifying paper provenance.

## Known failure modes

- Invalid or malformed DOI returns an error or null fields
- DOI not found in Crossref returns empty or null metadata
- Network timeout for slow upstream Crossref responses
- Missing required 'doi' field in request body returns validation error
- Some fields (e.g. references, license) may be null for older or grey-literature DOIs

## How this service works

Metadata of a publication by DOI (Crossref): title, authors, journal or publisher, year, type, citation count, references, license, link and an APA-formatted citation.

## Output

A JSON object containing the resolved paper's metadata: DOI, canonical URL, document type, publication year, page range, title, issue number, data source, volume, list of author names, journal name, license URLs, citation count, editorial/publisher name, reference count, and a pre-formatted APA citation string. Fields may be null if not available in the underlying Crossref metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "doi": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "doi": "10.1038/nature14539",
  "link": "https://doi.org/10.1038/nature14539",
  "type": "journal-article",
  "year": 2015,
  "pages": "436-444",
  "title": "Deep learning",
  "number": "7553",
  "source": "Crossref (metadatos)",
  "volume": "521",
  "authors": [
   "Yann LeCun",
   "Yoshua Bengio"
  ],
  "journal": "Nature",
  "license": [
   "https://www.springer.com/tdm",
   "https://www.springer.com/tdm"
  ],
  "citations": 78358,
  "editorial": "Springer Science and Business Media LLC",
  "references": 103,
  "apa_citation": "LeCun, Y., Bengio, Y., Hinton, G. (2015). Deep learning. Nature, 521(7553), 436-444. https://doi.org/10.1038/nature14539"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-doi-info-lookup-464d0946/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)