cpbox-batch-balance

Guide users on how to use the Batch EVM Address Balance Query API (/api/x402/batch-balance). Use when users ask about batch balance queries, multicall balance lookups, or how to call the x402-protected balance endpoint.

Batch EVM Address Balance Query API

Batch query EVM address balances via Multicall3, with pay-per-use powered by x402 protocol.

Prerequisites: This skill requires x402-payment. Complete the setup steps before first use.

Service URLs

Role	Domain
API Provider	https://www.cpbox.io
Facilitator	https://www.cppay.finance

Endpoint

POST /api/x402/batch-balance
Content-Type: application/json

Payment Flow (x402 Protocol)

This endpoint uses HTTP 402 Payment Required. The three-step flow:

1. First request (no payment header) -> Server returns 402 with payment requirements JSON
2. Client signs the payment requirements using EIP-712 -> Produces a PAYMENT-SIGNATURE
3. Retry with PAYMENT-SIGNATURE header -> Server verifies, settles, returns result JSON

When using @springmint/x402-payment (Node.js) or x402-sdk-go (Go), all 3 steps happen automatically.

Using with x402-payment

CLI (AI Agent)

npx @springmint/x402-payment \
  --url https://www.cpbox.io/api/x402/batch-balance \
  --method POST \
  --input '{"chain":"ethereum","token":"","addresses":["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045","0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8"]}'

Library (Node.js)

import { createX402FetchClient } from "@springmint/x402-payment";

const client = await createX402FetchClient();
const response = await client.request(
  "https://www.cpbox.io/api/x402/batch-balance",
  {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      chain: "ethereum",
      token: "",
      addresses: [
        "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
        "0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8",
      ],
    }),
  },
);
const data = await response.json();

• This endpoint uses EVM/ERC20 payments. See wallet configuration for setup options.

Request Parameters

Parameter	Type	Required	Description
chain	string	Yes	Chain name: ethereum, bsc, sepolia, etc.
token	string	No	ERC-20 contract address. Empty = native token (ETH/BNB)
addresses	[]string	Yes	Array of EVM addresses to query. Max 10,000. Must be 0x-prefixed, 42 chars.

Request Body Example

{
  "chain": "ethereum",
  "token": "",
  "addresses": [
    "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8"
  ]
}

Response

JSON with data array:

{
  "data": [
    {"address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045", "balance": "1500000000000000000", "error": ""},
    {"address": "0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8", "balance": "25000000000000000000", "error": ""}
  ]
}

balance is in smallest unit (wei). Divide by 10^decimals for human-readable value.

Go Example (Automatic Payment)

package main

import (
    "bytes"
    "context"
    "encoding/json"
    "fmt"
    "net/http"

    x402 "github.com/springmint/x402-sdk-go"
    "github.com/springmint/x402-sdk-go/mechanisms"
    "github.com/springmint/x402-sdk-go/signers"
)

func main() {
    signer := signers.NewEvmClientSigner("YOUR_PRIVATE_KEY_HEX")
    xClient := x402.NewX402Client()
    xClient.Register("eip155:*", &mechanisms.Permit402EvmClientMechanism{Signer: signer})
    xHttp := x402.NewX402HTTPClient(http.DefaultClient, xClient)

    reqBody := map[string]interface{}{
        "chain": "ethereum",
        "token": "",
        "addresses": []string{
            "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
            "0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8",
        },
    }
    bodyBytes, _ := json.Marshal(reqBody)

    resp, err := xHttp.RequestWithPayment(context.Background(), "POST",
        "https://www.cpbox.io/api/x402/batch-balance",
        string(bodyBytes),
        map[string]string{"Content-Type": "application/json"},
    )
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    var result struct {
        Data []struct {
            Address string `json:"address"`
            Balance string `json:"balance"`
            Error   string `json:"error"`
        } `json:"data"`
    }
    json.NewDecoder(resp.Body).Decode(&result)
    fmt.Printf("Done! Got %d results\n", len(result.Data))
}

cURL Example (Manual Two-Step)

Step 1 - Get payment requirements:

curl -X POST https://www.cpbox.io/api/x402/batch-balance \
  -H "Content-Type: application/json" \
  -d '{"chain":"ethereum","token":"","addresses":["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"]}'
# Returns HTTP 402 with payment requirements JSON

Step 2 - Pay and get result:

curl -X POST https://www.cpbox.io/api/x402/batch-balance \
  -H "Content-Type: application/json" \
  -H "PAYMENT-SIGNATURE: BASE64_ENCODED_SIGNED_PAYLOAD" \
  -d '{"chain":"ethereum","token":"","addresses":["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"]}'

ERC-20 Token Example

Query USDT balances on BSC:

curl -X POST https://www.cpbox.io/api/x402/batch-balance \
  -H "Content-Type: application/json" \
  -H "PAYMENT-SIGNATURE: ..." \
  -d '{
    "chain": "bsc",
    "token": "0x55d398326f99059fF775485246999027B3197955",
    "addresses": ["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"]
  }'

Error Codes

HTTP Code	Meaning
400	Bad request: missing addresses, no valid addresses, or >10,000 addresses
402	Payment required (first-time request, includes payment requirements)
500	Server error (RPC call failure)

Pricing

Each API call costs 0.0001 USDT (paid automatically via x402 protocol, supports BSC and TRON).

Supported Chains

Any EVM chain configured in the platform.