x402 Payment Harness: Making x402 Payments Without a Coinbase CDP Wallet

x402 Payment Harness: Making x402 Payments Without a Coinbase CDP Wallet The x402 protocol is elegant: an HTTP client hits an endpoint, gets a 402 Payment Required response, signs a USDC micropayment using EIP-712, and retries with an X-PAYMENT header. Server verifies, returns 200. No API keys, no subscriptions, no Stripe. The problem: every Python implementation assumed you had a Coinbase CDP wallet . If you're a protocol researcher, a server builder testing your own endpoints, or an agent developer who doesn't want CDP account creation + KYC-adjacent onboarding — you had no clean path. x402-payment-harness fixes this. pip install x402-payment-harness What it does A pure Python library + CLI that implements the full x402 protocol flow using any standard Ethereum EOA (a regular private key, no CDP required): HTTP GET /endpoint → 402 Payment Required + EIP-712 challenge → Local EIP-712 sign (TransferWithAuthorization) → Retry with X-PAYMENT header → 200 OK + receipt No Coinbase account.