Autonomous API Payments: Introducing the x402 Protocol

The Problem with API Monetization

Every API monetization system built in the last 20 years assumes there is a human with a credit card at the end of the line. You register, you give a card number, you get an API key. Then you pay a monthly bill.

That model breaks completely when the caller is an AI agent. Agents don't have credit cards. They don't fill out forms. They operate autonomously, at machine speed, often making thousands of calls across dozens of services.

How x402 Works

x402 is an open HTTP payment protocol. When an agent calls a paid endpoint, the server returns HTTP 402 Payment Required with machine-readable pricing information. The agent's wallet reads this, signs a USDC transfer on Solana, and retries the request with a payment proof header.

The entire flow takes under a second. No API keys. No monthly invoices. No registration. Capital moves atomically with the request.

Why Solana

Solana processes 65,000+ transactions per second with ~$0.00025 fees. For micropayments of $0.001–$0.01 per API call, this is the only chain where the economics work. Ethereum gas alone would exceed the payment value.

Metera is billing infrastructure for AI agents on Solana. Any API can charge agents automatically in USDC via the x402 protocol. metera.xyz