The HTTP 402 status code has existed since 1991. It was reserved for future use. "Payment Required." 35 years later, AI agents finally gave it a purpose. AI agents are already calling external APIs at scale. Claude, GPT, Gemini all have tool calling built in. The problem is there's no standard way to charge them. Until now.
What is x402
Most developers have never seen a 402 response. It was always theoretical. A status code with no real implementation. Coinbase changed that. x402 is an open protocol that turns HTTP 402 into a real payment layer. Here's how it works:
MonkePay lets you gate any API endpoint behind per-request USDC payments using the x402 protocol on Base. Add one middleware line. Agents pay automatically, no accounts, no billing setup, no chargebacks. You receive USDC directly to your wallet in seconds. Built for the autonomous agent economy where code pays code. Works with Express, Hono, Fastify, and Next.js today.
