# Vextorium DOI Metadata Lookup

> Vextorium DOI Metadata Lookup is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-16).

Returns publication metadata (title, authors, journal, year, type, citation count, references, license, link, and APA citation) for a given DOI via Crossref.

## Facts

- Endpoint: POST https://api.vextorium.com/doi-info-pago?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-doi-metadata-lookup-5cec92b5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-qzXrSLY_gEWRnP4y8zEI

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-metadata-lookup-5cec92b5 -d '<json body>'
```

Example prompt: Can you look up the full metadata for the paper with DOI 10.1038/nature12373 — I need the title, authors, journal, year, citation count, and an APA-formatted reference.

## When to prefer this

Choose this endpoint when you need structured bibliographic metadata for a known DOI, especially when an APA-formatted citation, citation count, or license information is needed. It is ideal for academic writing assistance, research enrichment pipelines, or any workflow that needs to resolve a DOI to its full Crossref record. Prefer this over a generic web search when structured, machine-readable metadata is required.

## Known failure modes

- DOI not found in Crossref — returns null fields or empty response
- Malformed or invalid DOI string — may return an error or null result
- Crossref rate limiting causing slow or failed response
- Some fields (e.g. license, references) may be null if the publisher has not deposited that metadata
- Non-journal content (datasets, preprints) may have incomplete metadata

## 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 with the paper's DOI, title, list of authors, journal or publisher name, volume, issue, pages, publication year, document type, citation count, reference count, license URLs, link to the article, and a pre-formatted APA citation string. Fields may be null if Crossref does not have that data for the given DOI.

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-doi-metadata-lookup-5cec92b5/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)