The Ethereum Foundation launched zkAPI on Ethereum mainnet on Thursday, October 1, 2026, according to The Block. It is a payment layer for AI services. It uses zero-knowledge proofs so that the party billing you cannot link a payment to the prompts you send. The protocol is labeled experimental in its GitHub repository.
The link it tries to cut
The Foundation’s launch post says: “Every AI API call today carries an identity.” An API key points to an account, the account to a payment method, and each prompt joins the record attached to both. zkAPI tries to break that chain between who pays and what they ask.
Step by step
- A user deposits ETH or USDC into an Ethereum vault contract. The balance is recorded as a private note.
- To spend, the user’s device generates a zero-knowledge proof that the request is backed by a funded note, without revealing which note.
- A zkAPI server verifies the proof and issues a temporary API key with a spending cap.
- The user sends prompts directly to the AI provider with that key. When the key expires, the server deducts the usage from the private balance.
- Each payment publishes a “nullifier,” a serial number. Spending the same balance twice produces a duplicate that exposes the attempt.
Forklog describes the split this way: the zkAPI server sees the payment and amount but not the requests, and the AI provider sees the prompts but not who paid. The local client exposes standard OpenAI and Ollama interfaces, so existing apps can connect through localhost, per The Block. Listed uses include AI chat and agents, blockchain RPC queries, image and video generation, VPN bandwidth and payments between AI agents.
| Party | Can see | Source |
|---|---|---|
| zkAPI server | Payment and amount, not requests | Forklog |
| AI provider | Prompts, IP address, not who paid | Forklog, The Block |
The underlying “ZK API Usage Credits” design was published on February 11 by Davide Crapis of the Foundation’s dAI team and Vitalik Buterin. The Foundation built zkAPI with the Open Anonymity Project. The launch post was written by Vittorio Rivabella, per The Block.
Why It Matters to You
- If you pay for AI tools and don’t want your payment tied to your prompts, this is an attempt at that. It is live on Ethereum mainnet, but experimental.
- You need ETH or USDC to deposit and software that supports it.
- Existing apps may connect through the local client, which mimics OpenAI and Ollama interfaces.
What it doesn’t hide
zkAPI gives no network anonymity. A gateway can correlate requests from a stable IP address, and The Block says Tor is suggested for stronger privacy. Prompt content can also re-link sessions, since personal details, writing style or conversation history can identify a user. The vault deposit is an on-chain transaction, so it carries normal Ethereum gas costs. Neither article reports a price, fee or savings figure, and neither source names supported AI providers, so apps need to be built or configured to work with it.
Quick answers
- Is zkAPI fully anonymous? No. Forklog says it does not provide full anonymity. IP addresses and writing style can still link activity.
- Is it live? Yes, on Ethereum mainnet since October 1, 2026, but marked experimental.
- What do I need to use it? ETH or USDC to deposit and software that supports it. The local client mimics OpenAI and Ollama interfaces.
- Is it safe to deposit large amounts? The sources call it experimental. Treat it as unaudited unless you find an audit report. This is not financial advice.
Sources
- The Block: Ethereum Foundation Launches zkAPI to Let Users Pay for AI Models Without Revealing Identity (Oct 1, 2026)
- Forklog: Ethereum Foundation Launches zkAPI for Private AI Payments (accessed Oct 13, 2026)