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Product, engineering and operating notes from the Harpd team.

x402 vs Mastercard Agent Pay vs Google AP2: which agent payment protocol should you use?

Compare x402, Mastercard Agent Pay, and Google AP2 payment protocols for your business. Learn about scalability, fees, integration, and security to make an informed decision.

Jul 19, 2026·3 min read

x402 in practice: charge-per-call from zero to first payment

An end-to-end x402 tutorial — set up a paid endpoint with HTTP 402, charge 0.01 USDC per call, observe every payment with the open-source SDK, and verify settlement onchain. No Harpd account required to follow along.

Jul 15, 2026·9 min read

Building Harpd

x402 vs Mastercard Agent Pay vs Google AP2: which agent payment protocol should you use?

x402 in practice: charge-per-call from zero to first payment

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