Ethereum Foundation launches zkAPI for private AI payments

The Ethereum Foundation and the Open Anonymity Project have deployed zkAPI on the Ethereum mainnet, a system for paying for AI models and other services on a pay-as-you-go basis without your billing identity following every prompt.

This is the first working version of a project designed by Davide Crapis and Vitalik Buterin. drawn on Ethereum Research.

• The problem : Today’s AI APIs work through card-linked accounts, so providers can group your prompts into one long profile under your name. That’s a lot of sensitive stories, like health issues and money worries, gathered in one place.

• How it works: You fund a vault contract on Ethereum once (the live vault contains USDC). From there, your device creates zero-knowledge (ZK) proofs, which show that you paid without revealing which deposit is yours, to unlock short-lived, spending-capped API keys. The payment server never sees your prompts and the AI ​​provider never sees who pays.

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• Plug and Play: A local client speaks standard OpenAI and Ollama interfaces, so existing applications can switch by pointing at it. There is also an option in the browser, OA Cat. Your balance remains withdrawable from the on-chain vault even if the zkAPI servers go down.

• Beyond chatbots: AI comes first, but the same setup can measure RPC requests, image generation, VPN bandwidth, and agent-to-agent payments without involving an account.

• The warnings: zkAPI only hides the payment link. Providers still see your IP address and what you type, and reused context like personal data or writing style can reconnect your sessions. For greater privacy, the team suggests going through Tor.

• Conclusion : For many people, AI chat logs may become the most revealing data trail they’ve ever left, and right now, that trail is saved under their real names. zkAPI is a first partial solution, but it’s a real-world case of Ethereum improving AI for today’s users. If AI agents end up transacting at scale, account-free meter payments like this could become standard plumbing.