561 Group Market

Project CITATION.cff

Project a paper.yaml into a CITATION.cff 1.2.0 file, valid against the official schema: humans first with the accountable author leading, an AI collaborator credited as a name entity with its disclosure, deterministic bytes. Returns the file text and its JSON value.

Price
$0.005 USDC per request
Network
Base mainnet, eip155:8453, settled in USDC through the Coinbase CDP facilitator
Method and URL
POST https://market.561.group/v1/project-citation-cff
Response type
application/json
Seller
Causeway Services (561 Group)

Input contract

Input that fails this contract is refused with a 4xx status before any payment is requested.

{
  "maxBytes": 65536,
  "bodySchema": {
    "type": "object",
    "additionalProperties": false,
    "properties": {
      "paper": {
        "type": "object",
        "description": "paper.yaml decoded as a JSON object."
      },
      "paperYaml": {
        "type": "string",
        "description": "paper.yaml source text."
      }
    }
  }
}

Example request

{
  "method": "POST",
  "url": "https://market.561.group/v1/project-citation-cff",
  "headers": {
    "accept": "application/json",
    "content-type": "application/json"
  },
  "body": {
    "paper": {
      "id": "example-paper",
      "title": "An Example Paper",
      "version": "1.0.0",
      "status": "released",
      "date-released": "2026-01-15",
      "abstract": "A short abstract describing the example paper.",
      "keywords": [
        "example",
        "metadata"
      ],
      "license": {
        "text": "CC-BY-4.0"
      },
      "authors": [
        {
          "given": "Ada",
          "family": "Lovelace",
          "affiliation": "Analytical Engine Society",
          "role": "accountable-human-author",
          "ai": false
        }
      ]
    }
  }
}

Output

{
  "schema": {
    "type": "object",
    "required": [
      "text",
      "value"
    ],
    "additionalProperties": false,
    "properties": {
      "text": {
        "type": "string",
        "description": "The file's exact bytes as UTF-8 text."
      },
      "value": {
        "description": "The same content as a JSON value."
      }
    }
  },
  "example": {
    "text": "cff-version: 1.2.0\nmessage: If you use this work, please cite it using the metadata from this file.\ntitle: An Example Paper\nversion: 1.0.0\ndate-released: \"2026-01-15\"\nabstract: A short abstract describing the example paper.\nauthors:\n  - family-names: Lovelace\n    given-names: Ada\n    affiliation: Analytical Engine Society\nkeywords:\n  - example\n  - metadata\nlicense: CC-BY-4.0\npreferred-citation:\n  type: report\n  authors:\n    - family-names: Lovelace\n      given-names: Ada\n      affiliation: Analytical Engine Society\n  title: An Example Paper\n  year: 2026\n  version: 1.0.0\n  notes: Not peer reviewed. No DOI assigned.\n",
    "value": {
      "cff-version": "1.2.0",
      "message": "If you use this work, please cite it using the metadata from this file.",
      "title": "An Example Paper",
      "version": "1.0.0",
      "date-released": "2026-01-15",
      "abstract": "A short abstract describing the example paper.",
      "authors": [
        {
          "family-names": "Lovelace",
          "given-names": "Ada",
          "affiliation": "Analytical Engine Society"
        }
      ],
      "keywords": [
        "example",
        "metadata"
      ],
      "license": "CC-BY-4.0",
      "preferred-citation": {
        "type": "report",
        "authors": [
          {
            "family-names": "Lovelace",
            "given-names": "Ada",
            "affiliation": "Analytical Engine Society"
          }
        ],
        "title": "An Example Paper",
        "year": 2026,
        "version": "1.0.0",
        "notes": "Not peer reviewed. No DOI assigned."
      }
    }
  }
}

How to buy with x402

  1. Send the request without payment. The server answers 402 Payment Required with a base64 JSON PAYMENT-REQUIRED header holding the amount, asset, network and payee.
  2. Have your wallet sign an EIP-3009 transferWithAuthorization for exactly those terms (an x402 client library does this for you).
  3. Repeat the identical request with the signed payload in the PAYMENT-SIGNATURE header.
  4. The server verifies, runs the operation, settles, and returns 200 with the result and a PAYMENT-RESPONSE header carrying the settlement receipt.

Read the price without paying

curl --include --request POST --header 'accept: application/json' --header 'content-type: application/json' --data-raw '{"paper":{"id":"example-paper","title":"An Example Paper","version":"1.0.0","status":"released","date-released":"2026-01-15","abstract":"A short abstract describing the example paper.","keywords":["example","metadata"],"license":{"text":"CC-BY-4.0"},"authors":[{"given":"Ada","family":"Lovelace","affiliation":"Analytical Engine Society","role":"accountable-human-author","ai":false}]}}' --url 'https://market.561.group/v1/project-citation-cff'

This request authorizes nothing; it returns the live payment terms. Read the full explanation of x402.

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