Ethereum Foundation Launches zkAPI for Private AI Payments
The EF and Open Anonymity's new zkAPI lets you prepay for AI and other APIs on Ethereum, then spend with ZK proofs so usage isn't tied back to you.
The Ethereum Foundation and the Open Anonymity Project have rolled out zkAPI on Ethereum mainnet, a system for paying for AI models and other per-use services without your billing identity following every prompt.
It's the first working build of a design that Davide Crapis and Vitalik Buterin sketched on Ethereum Research.
What’s the Scoop?
The problem: Today's AI APIs run through accounts tied to a card, so providers can stitch your prompts into one long profile under your name. That's a lot of sensitive history, like health questions and money worries, sitting in one place.
How it works: You fund a vault contract on Ethereum once (the live vault holds USDC). From then on, your device creates zero-knowledge (ZK) proofs, which show you've paid without revealing which deposit is yours, to unlock short-lived, spend-capped API keys. The payment server never sees your prompts, and the AI provider never sees who's paying.
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Plug and play: A local client speaks the standard OpenAI and Ollama interfaces, so existing apps can switch over by pointing at it. There's also an in-browser option, OA Chat. Your balance stays withdrawable from the vault onchain even if zkAPI's servers go dark.
Beyond chatbots: AI comes first, but the same setup can meter RPC queries, image generation, VPN bandwidth, and agent-to-agent payments with no accounts involved.
The caveats: zkAPI only hides the payment link. Providers still see your IP and what you type, and reused context like personal details or writing style can reconnect your sessions. For stronger privacy, the team suggests routing through Tor.
Bottom line: For many people, AI chat logs may become the most revealing data trail they ever leave, and right now that trail is filed under their real names. zkAPI is an early, partial fix, but it's a concrete case of Ethereum making AI better for users today. If AI agents end up transacting at scale, account-free metered payments like this could become standard plumbing.
William M. Peaster
William M. Peaster, Senior Writer, has been with Bankless since January 2021. Immersed in Ethereum since 2017, he covers the onchain frontier with a particular interest in art, games, and other culture apps. He has a background in creative writing and writes fiction in his free time.
