x402
An open payment protocol built on top of HTTP 402 that lets servers demand stablecoin payment before serving a resource, and lets clients (including autonomous AI agents) pay programmatically.
x402 is an HTTP-native payment protocol open-sourced by Coinbase in May 2025 that reactivates the HTTP 402 status code. Servers advertise payment requirements in response headers; clients - humans, scripts, or AI agents - sign a payment payload and retry the request, after which a stateless facilitator verifies the signature and settles the payment on-chain. The protocol is permissionless, chain-agnostic in principle, and targets micropayments, pay-per-call APIs, and agentic commerce. Governance moved to the Linux Foundation-hosted x402 Foundation in April 2026.
Related terms
- HTTP 402 - The reserved HTTP status code 'Payment Required' first defined in RFC 2068 (1997), carried forward in RFC 2616 and RFC 7231, and revived as
- Facilitator - A stateless service that verifies and settles x402 payments on behalf of a resource server so the server never needs to hold funds or integr
- Resource Server - Any HTTP service that exposes a paid endpoint under x402 - returning 402 until a valid payment proof is supplied.
- x402 SDK - Official and community SDKs that implement the x402 client and server flows for languages such as TypeScript, Python, and Go.
Recent stories
PROTOCOL
- Coinbase Q1 call: 99% of x402 settled in USDC, 90% of agentic stablecoin volume on Base - Choi calls x402 'the open standard for the next wave of agentic commerce' · theglobeandmail.com
- Circle ships Nanopayments on mainnet - gas-free USDC down to $0.000001 across 11 chains, fully x402 v2 compatible · circle.com
- Kite ships mainnet + Agent Passport - first x402-native chain with programmable agent wallets goes live · globenewswire.com
- Utexo enables USDT payments on x402 with near-instant Bitcoin-native settlement · prnewswire.com
- AWS Bedrock integrates x402 - first major cloud provider with native HTTP 402 payment rails for agents · cryptobriefing.com
BUILD
- x402station ships $1 Verified Badge - autonomous M2M trust layer flags 17% of x402 endpoints as non-functional · earezki.com
- Stripe Sessions 2026 ships Link Agent Wallet - x402 sits inside the 288-product agentic commerce stack · stripe.com
- Parallel Web Systems adds x402 to Search, Extract, and Deep Research APIs - $0.01 per call · docs.parallel.ai
- ChainAnalyzer ships x402 USDC payments on Base + Solana mainnet for its MCP server · dev.to
- DGrid AI adds x402 micropayments on BNB Chain - pay-per-call AI inference settled in USD1 within a single API request · cryptonews.net