561 Group Market

Unicode Text to Strict UTF-8 Bytes

Encode Unicode scalar text as exact RFC 3629 UTF-8 in a media-typed Base64 carrier. Preserve BOM, NUL and line endings; do not insert a BOM or normalize. Refuse lone surrogates and content over 65536 UTF-8 bytes before payment. Native Worker codec; no model or upstream API.

Price
from $0.0012 USDC per request (starting price; the 402 response quotes the exact amount for your input)
Network
Base mainnet, eip155:8453, settled in USDC through the Coinbase CDP facilitator
Method and URL
POST https://market.561.group/v1/data/text-to-utf8
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": 393344,
  "bodySchema": {
    "type": "object",
    "additionalProperties": false,
    "required": [
      "text"
    ],
    "properties": {
      "text": {
        "type": "string",
        "maxLength": 65536
      }
    }
  }
}

Example request

{
  "method": "POST",
  "url": "https://market.561.group/v1/data/text-to-utf8",
  "headers": {
    "accept": "application/json",
    "content-type": "application/json"
  },
  "body": {
    "text": "Pheží Ocháǧe 🛶"
  }
}

Output

{
  "schema": {
    "type": "object",
    "additionalProperties": false,
    "required": [
      "carrier",
      "byteLength"
    ],
    "properties": {
      "carrier": {
        "type": "object",
        "additionalProperties": false,
        "required": [
          "mediaType",
          "contentBase64"
        ],
        "properties": {
          "mediaType": {
            "const": "text/plain;charset=utf-8"
          },
          "contentBase64": {
            "type": "string",
            "maxLength": 87384,
            "description": "Canonical padded Base64 of at most 65536 strict UTF-8 bytes."
          }
        }
      },
      "byteLength": {
        "type": "integer",
        "minimum": 0,
        "maximum": 65536
      }
    }
  },
  "example": {
    "carrier": {
      "mediaType": "text/plain;charset=utf-8",
      "contentBase64": "UGhlxb7DrSBPY2jDocenZSDwn5u2"
    },
    "byteLength": 21
  }
}

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 '{"text":"Pheží Ocháǧe 🛶"}' --url 'https://market.561.group/v1/data/text-to-utf8'

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

Machine-readable