x402 payments for AI agent workflows

Blockchain address compliance and risk screening

Query BlockSec address labels and Phalcon Compliance risk screening through simple paid API endpoints. Each request is priced in USDC through the x402 protocol.

Starting at
$0.10
Payment rail
USDC Base
Access model
Per request
Supported chains
EthereumTronBNB ChainBasePolygonArbitrumOptimismAvalancheBitcoin

Try an endpoint

Select a service, chain, and address.

API catalog

Endpoints return JSON after a valid x402 payment.

Chain encoding

How to reference each chain in the /label/{chain}/{address} path, e.g. /label/ethereum/0x….

Show
Chain{chain} valuechain_id
Ethereumethereum1
Trontron-2
BNB Chainbnb56
Basebase8453
Polygonpolygon137
Arbitrumarbitrum42161
Optimismoptimism10
Avalancheavalanche43114
Bitcoinbitcoin-1

Abbreviations also accepted for compatibility: eth, bsc, matic, avax, btc. Matching is case-insensitive.

How agents use this API

Every endpoint is gated by the x402 payment protocol — pay per request in USDC on Base. No API key, no account.

Discover
GET /.well-known/x402.json lists every endpoint and its price (free, no payment).
Call & get 402
A plain request to /label/{chain}/{address} returns HTTP 402 with the USDC-on-Base payment requirements.
Pay & retry
An x402 client signs a gasless EIP-3009 authorization and retries with the X-PAYMENT header — the response is your JSON result.
Autonomous agent examplex402-fetchDemo only
Show
import { createWalletClient, http } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { base } from "viem/chains";
import { wrapFetchWithPayment } from "x402-fetch";

// Agent wallet, funded with USDC on Base
const account = privateKeyToAccount(process.env.AGENT_PRIVATE_KEY as `0x${string}`);
const wallet = createWalletClient({ account, chain: base, transport: http() });

// Wrap fetch: auto-handles 402 -> signs a gasless EIP-3009
// authorization -> retries with the payment header.
// 3rd arg caps spend per call (USDC base units): 1_000000n = $1.00,
// enough for deep screening (default is only 0.1 USDC).
const fetchWithPay = wrapFetchWithPayment(fetch, wallet, 1_000000n);

const res = await fetchWithPay(
  "https://x402.blocksec.ai/label/ethereum/0x463452c356322d463b84891ebda33daed274cb40",
);
console.log(await res.json());
Demo only. Never hardcode or expose a funded private key — in production, sign through a secure key manager (KMS/HSM) or the user's wallet.

Browser: open any endpoint URL directly and pay through the built-in wallet paywall.

Reference: BlockSec's open-source web3-companion agentic wallet uses exactly this flow.