x402
P2P ProtocolsOpen HTTP-native payment protocol that activates the dormant HTTP 402 'Payment Required' status code to enable instant stablecoin micropayments between clients and servers — including AI agents — without accounts, API keys, or KYC. A client receiving a 402 response pays in stablecoins and retries; the server grants access upon verification by a facilitator. Chain-agnostic, zero-protocol-fee, designed as a foundational internet primitive for the agentic economy. 100M+ payments processed since May 2025 launch.
Hybrid Foundation Medium capture risk
Links
Details
License Apache 2.0
Dev Status Released
Owner x402 Foundation (co-founded by Coinbase and Cloudflare, September 23, 2025); protocol created by Erik Reppel at Coinbase Developer Platform
Country USA
Start Year 2025
Stack TypeScript/JavaScript, Go, Rust
Funding Foundation
Last Investigated Jan 15, 2026
P2P Protocol Attributes
P2P Architecture Client-server (HTTP request-response with facilitator for payment verification and settlement)
Overlay Network N/A — HTTP transport
Content Addressing No
Local-First No
E2EE No (payment authorization in HTTP header; no E2EE channel established)
CRDTs Lib N/A
Byzantine Fault Tolerance N/A
Signature Yes — EIP-712 cryptographic signature on payment payload
Permissions Key-based (EIP-712 signed payment authorization; no account or API key required)
Semantic Web Compatability No
Smart Contract No (payment protocol; blockchain settlement via EVM/SVM facilitator)
Protocol Stack Position Application-layer (built on HTTP/HTTPS)
Asset / Value Embedding Application-layer add-on — value transfer handled via external blockchain facilitator, not embedded in the network packet
Protocol Maturity / Standardization Production / Open Standard — V2 specification released; x402 Foundation (Coinbase + Cloudflare) governs; 100M+ payments processed; ERC-8004 integration on roadmap; not submitted to IETF