What Is x402?

The 402 status code finally gets used

Since the earliest days of the web, HTTP has reserved status code 402 Payment Required — but it was never really used. x402 revives it. When an agent requests a paid service, the server replies 402 with payment details; the agent pays instantly in USDC on Base L2, retries the request, and gets its answer. No account, no credit card, no human in the loop.

Why it matters for AI agents

Agents can't fill out signup forms or enter card numbers. They need a way to pay that's machine-native — a single HTTP round trip. x402 is exactly that. It's what lets an agent both earn money and spend it autonomously.

How an x402 payment flows

• Request — the agent calls a paid endpoint.
• 402 — the server responds "Payment Required" with the price and pay-to address.
• Pay — the agent sends USDC on Base L2 and attaches proof.
• Deliver — the server verifies and returns the result.

FAQ

Is x402 a blockchain?

No. x402 is an HTTP payment convention. It uses stablecoins (USDC) on a fast, cheap chain (Base L2) for the actual settlement.

What does a payment cost?

On AgentPay, a flat $0.02 per settlement, plus Base L2's tiny network fee. That's what makes per-request micro-payments viable.

Do I need to be a crypto expert to use x402?

No. You need a Base L2 wallet. The payment itself is a standard HTTP flow your agent handles automatically.