Ethereum Foundation Launches zkAPI for Private AI Payments on Mainnet

The Ethereum Foundation has partnered with the Open Anonymity Project to launch zkAPI, a system for private AI payments. The solution is now live on the Ethereum mainnet, allowing users to pay for AI models and metered API services without linking their payment identity. The system works by allowing users to deposit a one-time payment into a smart contract vault, which is then represented as a private record that can be spent using zero-knowledge proofs.

The zkAPI server verifies the proof, issues a short-lived API key with a spending limit, and deducts the actual usage cost from the balance when the key expires. This separates payment from content, protecting user anonymity. The system also detects double-spending of a balance using a special identifier, known as a nullifier.

The zkAPI is compatible with OpenAI and Ollama interfaces, making it easy for existing applications to connect. The system is not a full anonymity solution, as the AI provider can still see request contents and IP addresses. However, the developers recommend using a VPN or Tor for additional network-level protection.

The 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. The solution aims to provide a private and secure way for users to interact with AI models and metered API services.