Ethereum Foundation Unveils zkAPI for Private AI Payments on Mainnet

The Ethereum Foundation and the Open Anonymity Project have launched zkAPI, a system for private AI payments on the mainnet of the second-largest cryptocurrency by market capitalization. This innovation allows users to pay for AI models and other metered API services without linking their requests to their payment identity.

According to the developers, a user makes a one-time deposit of ETH or USDC into a smart contract vault, which is then represented as a private record. This record can be spent using zero-knowledge proofs, allowing users to make private payments.

The zkAPI server sees only the fact of payment and the amount, not the requests themselves. The AI provider sees prompts but not who pays. The system detects double-spending of a balance using a special identifier, a nullifier.

While zkAPI does not provide full anonymity, it offers a significant improvement over traditional payment systems. The developers recommend using a VPN or Tor for network-level protection.

zkAPI is a working implementation of the ZK API Usage Credits concept, which was introduced in February by Ethereum Foundation dAI lead Davide Crapis and Ethereum co-founder Vitalik Buterin.