The zkAPI protocol uses locally generated zero-knowledge proofs to verify that a user has sufficient funds in a private note without disclosing which specific deposit belongs to the requester.

From the articleEthereum Foundation Rolls Out zkAPI for Anonymous AI Payments - BlockonomiAlso in Ethereum Foundation launches zkAPI to let users pay for AI models without revealing identity, Ethereum Foundation Launches Privacy Tool That Cuts the Link Between AI Prompts and Payers - Unchained, Ethereum targets AI privacy with zkAPI for anonymous API payments - Cryptopolitan