x402 Protocol Guide
x402 is an open internet-native payment standard that revives the dormant HTTP 402 'Payment Required' status code, enabling direct blockchain-based transactions over HTTP.
What is x402
x402 is an open internet-native payment standard that revives the dormant HTTP 402 'Payment Required' status code, enabling direct blockchain-based transactions over HTTP.
The entire payment lifecycle — pricing display, verification, settlement, and resource delivery — completes within a single HTTP conversation.
Key Features
HTTP Native Integration
Built directly into the HTTP protocol. Compatible with existing infrastructure (Express, Axios, Next.js). No additional communication protocols required.
Gasless Payments
Users don't need gas tokens (ETH, SOL). Facilitators cover gas costs. Payments in USDC only.
Micropayments
Minimum $0.001 per request. No API keys or subscriptions needed. Crypto signature-based authentication.
AI Agent Compatible
Supports autonomous AI agent payments. Agent-to-Agent (A2A) direct transactions enabled.
Ecosystem Metrics
Total Transactions
Payment Volume
Ecosystem Market Cap
Ecosystem
Key organizations participating in protocol development and operation
Protocol & Governance
Infrastructure
Payment