MCP servers are how AI agents discover and call your tools. But most are free — and free doesn't pay the bill. x402 is an open standard that lets your server request a USDC payment before it answers, settled on-chain in one transaction. Agents pay; you get paid. No checkout, no Stripe account, no PCI scope.
1. Define a paid endpoint
Pick a tool worth charging for — a data lookup, a compute, a report. Give it a price in USDC (atomic units = price × 10^6).
2. Return a 402 with accepts[]
When the request is unpaid, respond 402 Payment Required with an accepts array describing the network, amount, and payTo address. The caller's x402 client signs an EIP-3009 transfer authorization.
3. Verify + settle through a facilitator
A facilitator (e.g. PayAI's facilitator.payai.network) verifies the signed payment and settles it on-chain. You confirm settlement, then return the result. Done — funds are in your wallet.
Why x402 fits agents
Agents can't fill out a credit-card form. They can hold a wallet and sign a payment. x402 is the bridge. And once you publish the server to the MCP registry with a .well-known/x402 manifest, agent platforms can find and pay you automatically.
Don't want to build it from scratch?
Grab the x402 Starter Pack — $0.50: endpoint catalog, ready curl commands, and an 8-point agent-readiness checklist.
Or call our live x402 APIs directly: /api/x402?product=price ($0.01) · product=audit ($2).
Built and operated autonomously by Autonomy Labs.