# Ambolt DOI Lookup

> Ambolt DOI Lookup is a paid API for AI agents from api.ambolt.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-11).

Looks up scholarly publication metadata by DOI or citation text search, returning title, authors, year, publisher, citation count, and license information via the Crossref REST API.

## Facts

- Endpoint: GET https://api.ambolt.dev/v1/doi-lookup?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ambolt-doi-lookup-d1ce4c6b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JQ-forX3KK9mKMwAhR3KP

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 ambolt-doi-lookup-d1ce4c6b
```

Example prompt: Can you look up the metadata for DOI 10.1038/nature14539? I want the title, authors, year, journal, publisher, and how many times it's been cited.

## When to prefer this

Choose this endpoint when you need structured bibliographic metadata — authors, year, journal, publisher, citation count, license — for a known DOI or when searching by title/citation text. Ideal for academic research workflows, automated literature reviews, citation verification, or enriching datasets with scholarly metadata. Prefer over general web search when you need structured, machine-readable Crossref metadata rather than scraped HTML.

## Known failure modes

- Invalid DOI format (must match ^10\.\d{4,9}/\S+$) results in a validation error
- DOI not found in Crossref returns an empty works array
- Search query with no matching results returns count of 0
- Network timeout or Crossref API unavailability causes a service error
- Payment of $0.003 USDC required per call via x402 protocol; missing payment returns 402

## How this service works

Pay-per-call data tools for developers and AI agents: company registers, documents, tenders, rates and on-chain facts as MCP tools, x402 endpoints and Apify Actors.

## Output

Returns a JSON object containing the resolved DOI, canonical URL, article type, publication year, title, author list, license URLs, journal/container name, publisher name, cited-by count, reference count, data source attribution, and fetch timestamp. Up to 20 results can be returned per search query.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "POST"
     ]
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "doi": {
       "type": "string",
       "pattern": "^10\\.\\d{4,9}/\\S+$",
       "maxLength": 200,
       "description": "DOI, e.g. 10.1038/nature14539."
      },
      "limit": {
       "type": "integer",
       "default": 5,
       "maximum": 20,
       "minimum": 1,
       "description": "Maximum search results."
      },
      "query": {
       "type": "string",
       "maxLength": 300,
       "description": "Citation or title text to search when no DOI is known."
      }
     },
     "additionalProperties": false
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "doi": "10.1038/nature14539",
  "count": 1,
  "works": [
   {
    "doi": "10.1038/nature14539",
    "url": "https://doi.org/10.1038/nature14539",
    "type": "journal-article",
    "year": 2015,
    "title": "Deep learning",
    "authors": [
     "Yann LeCun",
     "Yoshua Bengio",
     "Geoffrey Hinton"
    ],
    "licenses": [
     "https://www.springer.com/tdm",
     "https://www.springer.com/tdm"
    ],
    "container": "Nature",
    "publisher": "Springer Science and Business Media LLC",
    "citedByCount": 77858,
    "referenceCount": 103
   }
  ],
  "source": "Source: Crossref REST API; metadata is available without restriction (CC0 facts).",
  "fetchedAt": "2026-10-02T21:35:41.793Z"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ambolt-doi-lookup-d1ce4c6b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.ambolt.dev](https://www.zero.xyz/host/api.ambolt.dev/llms.txt)