zkx402 — ZK-Verified Payment Protocol for AI Agents
zkx402's Team
Problem Statement
AI agents increasingly need to pay for API access, data, and compute — but current payment protocols treat all agents equally regardless of trust or identity. An anonymous bot pays the same as a verified institutional agent. There is no way for agents to prove credentials (human-verified, institutional affiliation) without revealing private data, and no mechanism for API providers to offer dynamic pricing based on verified identity. zkx402 solves this by embedding ZK proof verification directly into the HTTP 402 payment flow, enabling privacy-preserving identity-aware pricing for machine-to-machine transactions.
zkx402 extends the HTTP 402 payment protocol with zero-knowledge proof verification, enabling identity-aware micropayments for AI agents on Celo. When an agent requests paid API content, the server responds with 402 Payment Required alongside ZK proof metadata. The agent verifies content authenticity via ZK proofs, self-checks discount eligibility against its own credentials, and signs an EIP-3009 USDC payment — all in a single request cycle. Verified agents with valid ZK proofs (e.g., proof-of-human, institutional credentials) automatically receive discounted rates, creating a trustless reputation layer for machine-to-machine commerce. Built on Celo Sepolia with Circle USDC, the protocol demonstrates how x402 can evolve beyond simple paywalls into a sophisticated, privacy-preserving payment infrastructure where identity verification and payment happen atomically.
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zkx402
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Intention
Plans to continue
Planning to expand zkx402 into a general-purpose identity-aware payment layer for AI agent marketplaces, with support for more ZK proof types and additional chains