Ethereum Foundation Unveils zkAPI for Private AI Payments

The Ethereum Foundation has launched zkAPI, a system that enables users to pay for AI models and other metered APIs without revealing their identity. Built in collaboration with the Open Anonymity Project, zkAPI is designed to provide a private and secure way for users to access AI services.

To use zkAPI, users must first deposit tokens such as ETH or USDC into a vault contract on Ethereum, which records the user's balance as a private note. The user's software then generates a zero-knowledge proof, which shows that the request is backed by a funded note, without revealing which note or deposit funds it.

The zkAPI server checks the zero-knowledge proof and issues a temporary API key with a spending cap. The user can then send their prompts directly to the AI model provider along with the key, and when it expires, the server deducts the usage from the user's private balance.

The Ethereum Foundation's dAI team, led by Davide Crapis, has been working on this project since September 2025 to improve Ethereum's capabilities as a settlement and coordination layer for AI.