zkAPI Goes Live on Ethereum Mainnet, Offering Private Payments for AI Services

The Ethereum Foundation announced on Thursday that zkAPI is now running on Ethereum mainnet, turning an earlier zero-knowledge proposal into a working product. Built together with the Open Anonymity Project, the system lets people pay for AI and other API services without exposing their billing identity. It grows out of a February proposal from Ethereum Foundation researcher Davide Crapis and Ethereum co-founder Vitalik Buterin, who suggested ZK-based usage credits for metered APIs.

How Zero-Knowledge API Payments Work

According to Vittorio Rivabella, AI coordinator at the Foundation’s dAI team, users begin by depositing funds into an Ethereum vault. For each request, a zero-knowledge proof shows they hold enough credit without revealing which deposit belongs to them. The system issues short-lived API keys with preset spending limits, so payment and identity stay apart. Prompts go straight to the AI provider, while usage is settled separately through the payment layer.

Tools Released With zkAPI

The team has also published a local client, a software development kit and a browser based AI chat, giving developers and everyday users ways to try the system.

Privacy here has boundaries. zkAPI does not hide prompt contents or network metadata from providers, which means users could still be linked across sessions through IP addresses, request timing or information inside their messages.