# code402 — machine payment services on x402 (Base, USDC)

> This host sells verification and chain-data endpoints to AI agents.
> Every paid call settles USDC on Base via the x402 protocol (HTTP 402).
> Free: receipt verification is always free.

## Paid endpoints (x402, USDC on Base)

- POST /v1/verify/bundle — multi-gate compliance verification (IBAN, sanctions, onchain address) with XDR-1 signed receipt. Tiers: economy $0.005, standard $0.05, premium $0.50.
- GET /v1/chain/block-number — latest Ethereum block height. $0.005.
- GET /v1/chain/balance/:address — native ETH balance of an address. $0.005.
- GET /v1/chain/erc20/:token/:address — ERC20 balance via balanceOf. $0.005.
- GET /v1/chain/nonce/:address — next transaction nonce. $0.005.
- GET /v1/chain/tx/:hash — Ethereum transaction by hash. $0.008.
- GET /v1/chain/ens/:name — resolve a .eth name to an address. $0.008.

## Free endpoints

- POST /v1/receipt/verify — verify an XDR-1 signed receipt offline (keccak + signer recovery).
- GET /.well-known/agent.json — A2A agent card.
- GET /.well-known/mcp.json — MCP manifest for MCP clients.
- GET / — service descriptor.

## Payment protocol

x402 v2 on Base mainnet, USDC. A request without payment returns HTTP 402
with a PAYMENT-REQUIRED header carrying the accepted terms. Paying clients
resend with a payment-signature header; settlement is handled by the CDP
facilitator (https://api.cdp.coinbase.com/platform/v2/x402).

## Receipts

Paid bundle verifications return XDR-1 signed receipts, verifiable offline
against the published JWKS: https://hcrb.in/.well-known/jwks.json