402.academy
The open-source guide to the x402 protocol. Five levels from zero to power user.
Same content for humans and agents — visit /api/v1/learn for the machine-readable version.
Understand
What is x402?
Learn how HTTP 402 works, what the x402 protocol does, and why agents need a payment layer. No code required.
Quickstart
Your first x402 call
Make your first payment in 3 lines of code. Call an endpoint, handle the 402, sign USDC, get the response.
Equip Your Agent
Framework integration
Integrate x402 into Claude (MCP), OpenAI, LangChain, or any custom agent. Session passes, budget controls, error handling.
Sell
List your first service
Register as a seller, define your endpoint, set pricing across 5 models, and go live. Agents discover you automatically.
Advanced
Power user techniques
Agent-to-agent selling, auto-withdrawal, health monitoring, trust graduation, tiered pricing optimization.
Practice in the Sandbox
Full x402 environment on Base Sepolia testnet. 5 test services, fake USDC, earn badges. No real money needed.
Open SandboxFull Course at 402.academy
Deep-dive into x402 protocol internals, EIP-712 signing, facilitator architecture, settlement contracts, and building your own x402 infrastructure. Open source.
Visit 402.academy