Stripe x402 vs Machine Payments Protocol: Which One Should You Build On?
Two agent payment protocols shipped in Q1 2026. Coinbase's x402 went live on Base with USDC settlement. Stripe and Paradigm's Machine Payments Protocol (MPP) launched on Tempo's chain on March 18, the same day. Both let AI agents pay for services. Both have Stripe integration. They are not the same thing. I build on x402. This post explains both protocols factually, compares the trade-offs, and explains why I chose the one I did. If you're building a paid API or an agent that needs to pay for things, this comparison matters. x402: Per-Request Settlement x402 uses the HTTP 402 status code as a payment trigger. The flow: agent requests a resource, server responds 402 with a price and wallet address, agent signs a USDC payment, retries the request with payment proof, server verifies and delivers the data. Every payment settles independently on-chain. One request, one transaction, one settlement. The agent doesn't need an account, an API key, or a pre-existing...