561 Group Market

Base Address Balance

Native ETH balance for one Base network address, read live from a public Base RPC node (eth_getBalance) and returned with the snapshot block it was read at.

Price
$0.001 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/base-chain/balance
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.

{
  "querySchema": {
    "type": "object",
    "properties": {
      "address": {
        "type": "string",
        "pattern": "^0x[0-9a-fA-F]{40}$",
        "description": "The Base network address to read."
      }
    },
    "required": [
      "address"
    ]
  }
}

Example request

{
  "method": "GET",
  "url": "https://market.561.group/v1/base-chain/balance?address=0x4200000000000000000000000000000000000006",
  "headers": {
    "accept": "application/json"
  }
}

Output

{
  "schema": {
    "type": "object",
    "required": [
      "address",
      "weiBalance",
      "snapshotBlock"
    ],
    "properties": {
      "address": {
        "type": "string"
      },
      "weiBalance": {
        "type": "string"
      },
      "snapshotBlock": {
        "type": "string"
      }
    }
  },
  "example": {
    "address": "0x4200000000000000000000000000000000000006",
    "weiBalance": "1000000000000000000",
    "snapshotBlock": "100"
  }
}

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 GET --header 'accept: application/json' --url 'https://market.561.group/v1/base-chain/balance?address=0x4200000000000000000000000000000000000006'

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

Machine-readable