The Ethereum Foundation launched zkAPI on Thursday, a system that lets users pay for AI models and other pay-per-use APIs without revealing who they are. It was developed together with the Open Anonymity Project and is now live on the Ethereum mainnet. To use it, users deposit tokens such as ETH or USDC into a vault contract on Ethereum, which records the balance as a private note. Client-side software generates a Zero-Knowledge Proof to show that a request is backed by a funded note without revealing which note it is. The zkAPI server verifies this and issues a temporary API key with a capped spending limit, then deducts usage from the private balance when the key expires. A Nullifier serial number is published every time a payment is made to prevent double-spending. The system does not provide network-level privacy, since the gateway may link requests from a static IP address and sessions may be re-linked through prompt content. The GitHub repository notes that the protocol is still experimental. zkAPI puts into practice the ZK API Usage Credits concept, a design by Davide Crapis and Ethereum co-founder Vitalik Buterin published on the Ethereum Research forum on February 11. Crapis leads the foundation's dAI team, which was set up in September 2025, and the team also developed ERC-8004, a standard for AI agent identity that launched on mainnet in January. The blog post announcing zkAPI was written by Vittorio Rivabella of the dAI team.
EthereumEthereum Foundation launched zkAPI on Ethereum mainnet, a new privacy-preserving payments system built on Ethereum.
USD CoinUSDC is named as one of the tokens users can deposit into the zkAPI vault contract, giving it a concrete new use case.
