561 Group Market

Koios Intelligence Briefing

The current Koios intelligence issue: bounded source-led analysis with every section linked to its cited evidence.

Price
$0.25 USDC per request
Network
Base mainnet, eip155:8453, settled in USDC through the Coinbase CDP facilitator
Method and URL
GET https://market.561.group/v1/koios/briefing/current
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.

{}

Example request

{
  "method": "GET",
  "url": "https://market.561.group/v1/koios/briefing/current",
  "headers": {
    "accept": "application/json"
  }
}

Output

{
  "schema": {
    "type": "object",
    "required": [
      "kind",
      "id",
      "issuedAt",
      "title",
      "sections",
      "references"
    ],
    "properties": {
      "kind": {
        "const": "koios.news.intelligence-briefing/v1"
      },
      "id": {
        "type": "string"
      },
      "issuedAt": {
        "type": "string"
      },
      "title": {
        "type": "string"
      },
      "sections": {
        "type": "array",
        "minItems": 1
      },
      "references": {
        "type": "object"
      }
    }
  },
  "example": {
    "kind": "koios.news.intelligence-briefing/v1",
    "id": "koios-intelligence-briefing:2026-09-24:2026-09-25",
    "issuedAt": "2026-09-25T00:00:00.000Z",
    "title": "Koios Intelligence Briefing",
    "sections": [
      {
        "heading": "A sourced development",
        "body-markdown": "A bounded evidence-led summary.",
        "sources": [
          "https://example.com/source"
        ]
      }
    ],
    "references": {
      "https://example.com/source": {
        "id": "https://example.com/source",
        "type": "webpage",
        "title": "Source",
        "URL": "https://example.com/source"
      }
    }
  }
}

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.

This offer is recoverable: save a random X-Payment-Recovery token before paying and repeat the same signed request with it to receive the exact purchased response again if the connection drops.

Read the price without paying

curl --include --request GET --header 'accept: application/json' --url 'https://market.561.group/v1/koios/briefing/current'

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

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