Identity & Enrichment · x402 · early usage

Search open Crossref bibliographic metadata by title, author, DOI fragment, or citation…

Search open Crossref bibliographic metadata by title, author, DOI fragment, or citation and return bounded normalized publication, author, citation, license, and update metadata without abstracts or full text.

by apiacre.com · discovered, not yet claimed by its owner · updated 2026-10-08

30d calls1

30d payers1

MethodPOST

Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

Tags: scholarly-search · research-papers · doi-search · publication-metadata · citations · bazaar · payment-identifier

Call contract

Method: POST
Input: json
Output: json
Last paid call: 2026-10-08

Input example from Bazaar metadata

{
  "max_results": 5,
  "query": "agentic commerce payment protocols",
  "sort_by": "relevance",
  "work_type": "journal-article"
}

Output example

{
  "data": {
    "documentation": "https://www.crossref.org/documentation/retrieve-metadata/rest-api/",
    "limitations": [
      "Demonstration metadata only; paid calls return current publisher-deposited re...",
      "Abstracts and full text are deliberately excluded."
    ],
    "metadataLicense": {
      "abstractsReturned": false,
      "name": "Open bibliographic metadata / Crossref-generated data CC0",
      "url": "https://www.crossref.org/documentation/retrieve-metadata/"
    },
    "query": {
      "bibliographic": "agentic commerce payment protocols",
      "publishedFrom": null,
      "publishedUntil": null,
      "sortBy": "relevance",
      "workType": "journal-article"
    },
    "results": [
      {
        "authors": [
          {
            "affiliations": [
              "Example Institute"
            ],
            "family": "Example",
            "given": "Ada",
            "name": "Ada Example",
            "orcid": null
          }
        ],
        "doi": "10.1000/apiacre.example",
        "publishedDate": "2026-08-20",
        "title": "A bounded example scholarly work",
        "type": "journal-article"
      }
    ],
    "resultsReturned": 1,
    "retrievedAt": "2026-08-20T12:00:00+00:00",
    "source": "https://api.crossref.org/works",
    "totalResults": 1
  },
  "meta": {
    "cached": false,
    "duration_ms": 42,
    "next_actions": [
      {
        "method": "POST",
        "path": "/v1/research/crossref-doi-metadata",
        "reason": "Resolve one selected scholarly-search candidate into a focused current DOI me...",
        "service": "research.crossref-doi-metadata",
        "title": "Crossref DOI metadata enrichment"
      }
    ],
    "sources": [],
    "warnings": []
  },
  "request_id": "018f1f54-7f38-7ba2-8dc3-5f90272d9f1a",
  "service": "research.crossref-work-search",
  "version": "1"
}

Use with an agent

Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
Inspect. Fetch /resources/27755.json for the price and payment options.
Pay. Call GET https://apiacre.com/v1/research/crossref-work-search. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Solana, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price: $0.008 / request
Protocol: x402 v2
Auth: No account or API key. Pay per request.
Networks: Base, Solana
Demand: 1 calls · 1 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

Scheme	Network	Asset	Amount	Pay to	Timeout
exact	Base eip155:8453	USDC	$0.008	0xa0BFa4f07281c9b248DC3AED2217836BcA24869B	300s
exact	Solana solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp	USDC	$0.008	B4CHWQeQn7GDLZD2aW6hpGG2bEseisBFLZYECA3HDLan	300s

accepts[] (raw JSON)

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xa0BFa4f07281c9b248DC3AED2217836BcA24869B",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "8000",
    "amountUsd": 0.008,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "B4CHWQeQn7GDLZD2aW6hpGG2bEseisBFLZYECA3HDLan",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "8000",
    "amountUsd": 0.008,
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)

{
  "properties": {
    "example": {
      "properties": {
        "data": {
          "properties": {
            "documentation": {
              "type": "string"
            },
            "limitations": {
              "items": {},
              "type": "array"
            },
            "metadataLicense": {
              "type": "object"
            },
            "query": {
              "type": "object"
            },
            "results": {
              "items": {},
              "type": "array"
            },
            "resultsReturned": {
              "type": "integer"
            },
            "retrievedAt": {
              "type": "string"
            },
            "source": {
              "type": "string"
            },
            "totalResults": {
              "type": "integer"
            }
          },
          "type": "object"
        },
        "meta": {
          "properties": {
            "cached": {
              "type": "boolean"
            },
            "duration_ms": {
              "type": "integer"
            },
            "next_actions": {
              "items": {
                "type": "object"
              },
              "type": "array"
            },
            "sources": {
              "items": {
                "type": "string"
              },
              "type": "array"
            },
            "warnings": {
              "items": {
                "type": "string"
              },
              "type": "array"
            }
          },
          "required": [
            "duration_ms",
            "cached",
            "sources",
            "warnings",
            "next_actions"
          ],
          "type": "object"
        },
        "request_id": {
          "type": "string"
        },
        "service": {
          "type": "string"
        },
        "version": {
          "type": "string"
        }
      },
      "required": [
        "request_id",
        "service",
        "version",
        "data",
        "meta"
      ],
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}

Example shape — generated from the schema, not a captured live response

{
  "example": {
    "data": {
      "documentation": "string",
      "limitations": [
        "value"
      ],
      "metadataLicense": {},
      "query": {},
      "results": [
        "value"
      ],
      "resultsReturned": 0,
      "retrievedAt": "string",
      "source": "string",
      "totalResults": 0
    },
    "meta": {
      "cached": true,
      "duration_ms": 0,
      "next_actions": [
        {}
      ],
      "sources": [
        "string"
      ],
      "warnings": [
        "string"
      ]
    },
    "request_id": "string",
    "service": "string",
    "version": "string"
  },
  "type": "string"
}

Examples

curl

curl -X POST 'https://apiacre.com/v1/research/crossref-work-search' -H 'Content-Type: application/json' --data '{"max_results":5,"query":"agentic commerce payment protocols","sort_by":"relevance","work_type":"journal-article"}'
# -> 402 Payment Required; read PAYMENT-REQUIRED
# retry the identical request with PAYMENT-SIGNATURE

JavaScript

const res = await fetch("https://apiacre.com/v1/research/crossref-work-search", {
  "method": "POST",
  "headers": {
    "content-type": "application/json"
  },
  "body": "{\"max_results\":5,\"query\":\"agentic commerce payment protocols\",\"sort_by\":\"relevance\",\"work_type\":\"journal-article\"}"
});
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

Python

import httpx
import json
res = httpx.request("POST", "https://apiacre.com/v1/research/crossref-work-search", json=json.loads("{\"max_results\":5,\"query\":\"agentic commerce payment protocols\",\"sort_by\":\"relevance\",\"work_type\":\"journal-article\"}"))
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider: apiacre.com
Endpoint: https://apiacre.com/v1/research/crossref-work-search
Machine-readable: /resources/27755.json