What is the x402 (x402)?
Last verified 2026-06-18x402 is an open payment standard launched by Coinbase on 6 May 2025 that carries native stablecoin payments over HTTP by reviving the dormant 402 "Payment Required" status code. It lets apps, APIs and AI agents pay per request without accounts or API keys. Settlement happens on-chain through facilitators (Base, Polygon, Arbitrum, World, Solana), with the first "exact" scheme using EIP-3009. It launched with AWS, Anthropic, Circle and NEAR, is licensed under Apache 2.0, and its specification has since moved to the x402 Foundation.
Key facts
| Author / steward | Created by Coinbase; specification stewarded by the x402 Foundation |
|---|---|
| Announced | 2025-05-06 |
| License | Apache 2.0 |
| Governance | Launched by Coinbase; the specification was transferred to the x402 Foundation (the coinbase/x402 repository is now a development fork); homepage x402.org |
| Scope | An open payment standard for internet-native payments built on the HTTP 402 (Payment Required) status code; transport-agnostic, designed for humans, apps and AI agents |
| Transport | HTTP (402 status code and payment headers); transport-agnostic, with MCP and A2A representations |
| Payment | On-chain stablecoin settlement via facilitators; first scheme exact (EIP-3009 gasless ERC-20); supports Base, Polygon, Arbitrum, World and Solana |
| Maturity | stable |
What makes it distinctive
- Launched by Coinbase on 6 May 2025
- Revives the dormant HTTP 402 Payment Required status code for native payments
- Launched with collaborators AWS, Anthropic, Circle and NEAR
- On-chain settlement via facilitators; exact scheme uses EIP-3009
- Specification transferred to the x402 Foundation; licensed under Apache 2.0
- Surpassed 100 million transactions on Base by June 2026, per Chainalysis
- Coinbase and AWS integrated x402 into Amazon Bedrock AgentCore Payments and AWS CloudFront and WAF in June 2026
How x402 works
x402 revives the dormant HTTP 402 Payment Required status code. A server answers a request with 402 plus machine-readable payment requirements; the client (an app, API consumer or AI agent) submits a signed payment and retries; a facilitator verifies and settles the payment on-chain so sellers do not run blockchain infrastructure. The first scheme, exact, uses EIP-3009 (USDC, EURC) with Permit2 as an alternative; settlement is available on Base, Polygon, Arbitrum, World and Solana. No accounts, no API keys: payment is bound to the request itself.
Specification and governance
Coinbase launched x402 on 6 May 2025 alongside AWS, Anthropic, Circle and NEAR. It is Apache 2.0; the specification has since moved to the x402 Foundation, with coinbase/x402 remaining as a development fork (homepage x402.org). Visa announced collaboration with Coinbase on TAP/x402 interoperability in October 2025.
How x402 fits the stack
x402 is the machine-to-machine, on-chain payment rail of the stack: it suits pay-per-call APIs and autonomous agent spending rather than retail checkout. AP2 reaches crypto through the A2A x402 extension. The closest neighbor is MPP (Tempo + Stripe, March 2026), which uses a similar HTTP payment-request flow but spans stablecoins and fiat via Shared Payment Tokens.
Limitations and open questions
Settlement today is on-chain stablecoins via facilitators, which means crypto rails and their regulatory context; card and bank-transfer flows are out of scope. For human-facing retail checkout, ACP and UCP are the relevant standards; x402 wins where the buyer is software.
Who should care
API providers wanting to charge per request without accounts, agent builders giving agents spending ability, and anyone exploring machine-native business models.