Level 4 · Expert · 7 min

x402

HTTP 402 Payment Required, revived as a per-call payment protocol for agents. Powers Agentic Market.

x402 turns the dormant HTTP 402 status code into a working micropayment handshake. An agent calls a service, gets a 402 with payment instructions, settles the payment, retries the call with proof, and gets the response.

The protocol is custodied infrastructure (Coinbase Developer Platform, Linux Foundation governance). Agents pay per request. No account, no signup, no rotating API keys to manage.

Solid State exposes a subset of skills as x402 services on Agentic Market.