Notes on x402 and the agent economy.

Pay-per-call APIs are a brand-new category. We write about how they work, who's building them, and how to ship one yourself.

• Jun 12, 2026 · 6 min read

  What is x402? The HTTP status code becoming the payment layer for AI agents

  x402 is an open protocol that turns HTTP 402 Payment Required into a real, machine-readable payment handshake. Here's how it works and why Coinbase, Stripe, and Adyen are backing it.

• Jun 11, 2026 · 7 min read

  x402 vs Stripe vs RapidAPI: which billing model fits your API?

  Subscriptions, usage-based billing, and pay-per-call all sound similar. They aren't. A direct comparison of x402, Stripe metered billing, and the RapidAPI marketplace for API providers.

• Jun 10, 2026 · 5 min read

  How to monetize an API with x402 in under 10 minutes

  Step-by-step: take any HTTP endpoint you own, plug in x402 middleware, list it on a pay-per-call marketplace, and start collecting USDC per request.