x402-buyer

Overview ¶

x402-buyer is a lean sidecar that handles x402 payments using pre-signed ERC-3009 TransferWithAuthorization vouchers. It runs as an OpenAI-compatible reverse proxy in the llm namespace, alongside LiteLLM.

LiteLLM sees the sidecar as a plain OpenAI provider. The sidecar intercepts 402 responses from upstream sellers, attaches pre-signed payment headers, and retries. It has zero signer access — spending is bounded by the number of pre-signed authorizations in the pool.

Usage:

x402-buyer --config /config/config.json --auths /config/auths.json --listen :8402