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x402 is an open, HTTP-native payment standard maintained by the Coinbase Developer Platform. It activates the long-dormant 402 Payment Required status so any API, website, or agent can charge small crypto-denominated fees without building custom billing flows.
The V1 specification focuses on flat-rate micropayments using the X-PAYMENT header and a standard JSON schema for negotiating payment requirements between clients, resource servers, and facilitators.

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Why x402 matters

  • Open standard, no rent seeking: The protocol is stewarded in the open, and implementations (client, server, facilitator) can be built by anyone. (coinbase/x402)
  • HTTP-native integration: Payments ride on ordinary HTTP requests and responses—no extra sign-in, OAuth, or signature exchanges. (x402.org)
  • Chain & asset agnostic: Any (scheme, network) pair can be registered so you can settle on Base, L2s, or other chains that meet the spec.
  • Trust-minimized settlement: Resource servers never take custody of user funds; a facilitator verifies receipts on-chain and can optionally settle on the server’s behalf.
  • Agent-friendly micropayments: Fees can be as low as $0.001 with ~2 second settlement, enabling AI agents and bots to pay per-request.

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Core roles in the ecosystem

RoleResponsibility
ClientRequests a protected resource and composes X-PAYMENT payloads.
Resource serverExposes the API/content and responds with 402 when payment is required.
Facilitator serverOptional third party that verifies and settles payments so the resource server does not need direct chain access.

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Schemes & networks

  • Schemes describe how value is moved. The first shipping scheme is exact, which transfers a fixed amount (e.g., “pay $0.01 for this request”). Future schemes like upto add metered usage.
  • Networks scope those schemes to a blockchain implementation (for example, exact on Base differs from exact on Solana). Clients, facilitators, and servers must explicitly agree on the (scheme, network) pair.
x402 is built to be extensible: see specs/schemes for latest proposals, and ROADMAP.md for upcoming protocol milestones.

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Developer resources

Stay up to date by watching the coinbase/x402 repository; the spec and tooling are evolving quickly as more facilitators and payment schemes come online.