px402 is a zero-knowledge payment protocol that enables AI agents to make anonymous, untraceable payments on-chain. In a world where every blockchain transaction is public by default, AI agents conducting autonomous transactions create massive privacy leaks—revealing their strategies, counterparties, and financial behavior to competitors and surveillance systems. px402 solves this by combining zero-knowledge cryptography with ERC-4337 account abstraction, allowing agents to spend funds privately without linking transactions to their identity or previous activity.