metadata
title: x402 Protocol Specification
emoji: 💳
colorFrom: green
colorTo: gray
sdk: static
sdk_version: ''
app_file: README.md
pinned: false
license: mit
x402 Protocol Specification
HTTP 402 Payment Required for AI agent micropayments.
Overview
x402 is the production implementation of HTTP 402 (reserved since 1998) for the autonomous agent economy. It enables machine-to-machine micropayments over USDC on Solana.
How It Works
- Agent requests a protected resource → HTTP 402 with payment challenge
- Agent parses challenge, submits USDC payment on Solana
- Gateway confirms settlement (~2-3 Solana slots)
- Protected resource is returned
Total round trip: < 3 seconds. No humans. No redirects. No API keys.
Specification
Status: v0.2.0 (active)
Implementations
| Implementation | Language | Status |
|---|---|---|
| NullState Gateway | Python | Production |
| Coinbase AgentKit | TypeScript | Beta |
| AEON Protocol | Rust | Beta |
License
MIT — do whatever you want.