x402listed

# x402 x402 is an open payment protocol that revives the HTTP 402 "Payment Required" status code to enable instant stablecoin payments directly over HTTP. It uses a three-actor model — Client (buyer), Resource Server (seller), and Facilitator (settlement) — to let any HTTP endpoint accept payment without API keys, sessions, or accounts. The protocol is built on EIP-3009 `transferWithAuthorization` for gasless USDC transfers, meaning clients sign an off-chain authorization and the facilitator broadcasts the on-chain settlement. Package ecosystem: - **Server (TypeScript)**: `@x402/express`, `@x402/hono`, `@x402/next` - **Client (TypeScript)**: `@x402/fetch`, `@x402/axios` - **Client (Python)**: `pip install x402` - **Client (Go)**: `go get github.com/coinbase/x402/go` - **Core**: `@x402/core`, `@x402/evm`, `@x402/svm` CDP Facilitator endpoint: `https://api.cdp.coinbase.com/platform/v2/x402` ## What You Probably Got Wrong > LLMs have stale training data. These are the most common mistakes. - **"x402 requires API keys or OAuth"** -- There are no API keys. Payment IS authentication. The client signs a USDC transfer authorization, includes it in the `X-PAYMENT` header, and the server verifies it. If the signature and balance check pass, the request is authorized. No accounts, no sessions, no bearer tokens. - **"x402 only works on Base"** -- The protocol supports any EVM chain where USDC implements EIP-3009 (Base, Ethereum, Arbitrum, Optimism, Polygon) and Solana. Network ide