Ethereum Foundation Unveils zkAPI: Zero-Knowledge Payments for AI Services
The Ethereum Foundation and the Open Anonymity Project have launched zkAPI on October 1, 2026. This new payment system allows users to pay for metered APIs with zero-knowledge proofs instead of revealing their identity.
Users deposit credits into an Ethereum vault contract, which generates a private cryptographic note that only they can spend. The software on their device then creates a zero-knowledge proof authorizing bounded spending without exposing the user's identity.
The AI provider receives a temporary, capped API key and doesn't learn who is behind it. Only the deposits and withdrawals are recorded on Ethereum's public ledger.
This design relies on Groth16 zero-knowledge proofs over the BN254 elliptic curve, Poseidon hashing, and a 32-level Merkle tree to track commitments without exposing underlying data.