Ethereum Foundation Jointly Launches Mainnet zkAPI
The Ethereum Foundation and Open Anonymity Project announced the joint launch of zkAPI on October 1, stating that it is now operational on the Ethereum mainnet. Users can deposit ETH or USDC into a treasury contract once, and then authorize amounts using zero-knowledge proofs without revealing their payment identity to service providers.
The foundation's blog post was published by Vittorio Rivabella from the dAI team. The design corresponds to research published by Ethereum co-founder Vitalik Buterin and dAI head Davide Crapis on February 11. The mainnet contract records amounts as USDC credit, with the same set of tests deployed on Sepolia.
Service providers can see the request content but not the payer. The payment layer can only see the consumption amount and cannot link the amount to a specific request or user. On-chain records only include deposits, settlements, and withdrawals, without noting which service the funds were used for. User devices generate proofs indicating that a certain amount of funds is sufficient to cover the current consumption and has not been used previously. After off-chain verification by the server, a temporary key with a limit and validity period is issued.
Users can directly request service providers using this key. Service providers record actual usage and generate signed receipts, and the system deducts from the private balance according to actual usage. The proof uses Groth16, with a curve of BN254, and commitment and cancellation symbols using Poseidon hash, with the state stored in a 32-layer Merkle tree. The treasury is controlled by Ethereum contracts. If the server goes down, users can withdraw funds directly from the chain without server cooperation.
The first scenario is artificial intelligence inference. The foundation states that currently every API call carries identity, with keys pointing to accounts, and accounts pointing to payment methods, merging prompts into the same file. Health and finance-related prompts are therefore prioritized for separation. The same mechanism can also be used for blockchain RPC, image, and video generation interfaces that charge based on usage.
The buyer is a model user who does not want to link prompts and payment identity, while the seller is an API service provider that still charges based on usage. This is a settlement diversion driven by product launch, not a new token issuance. Beneficiaries are inference users seeking anonymous limits and service providers willing to connect to this treasury. Those under pressure are model platforms that price based on long-term account profiles and data merchants treating payment addresses as user identities.
Mainnet operation means that the treasury and proof process are available. The announcement did not specify how many model service providers are connected, the scale of deposits, or actual usage.
Source: Public Information
ABAB AI Insight
The Ethereum Foundation is pushing zero-knowledge from scalability proofs to application layer privacy after 2024. Buterin and Crapis framed the issue of usage-based APIs in February 2026: prompts are sensitive, but payments must leave a trace. The Open Anonymity Project is responsible for turning this design into a functioning system, launched on the mainnet on October 1. The approach is not to issue a new chain but to add a layer of proof that cannot link requests and payments on the existing treasury.
Funds first convert into USDC credit in the treasury, then user devices prove "this amount is sufficient and has not been spent before." Service providers receive temporary keys and requests, while the payment layer only sees the amount. Neither side can access the other's half. If the server goes down, the contract still allows withdrawals, effectively leaving the custody risk on Ethereum rather than with the API company. Groth16, BN254, Poseidon, and the 32-layer Merkle tree are the implementations of this separation, not new assets.
A comparison can be made to how Zcash separated payers and payees after 2013, and how Tornado Cash separated deposits and withdrawals after 2020, leading to sanctions. The difference is that zkAPI separates request content and payment identity, while service providers still need to see prompts to complete inference. The industry is in an expansion phase. AI APIs are already charging based on tokens, and the privacy layer has just transitioned from papers to mainnet contracts. The connected parties have not yet been publicly named.
Structurally, this represents a transfer of pricing power. Model companies previously used API keys to compile years of prompt data into a single profile, which itself was the product. The mechanism places payment proof on user devices and off-chain verification, leaving only deposits and settlements on-chain. Service providers can read requests but cannot identify whose money it is. Therefore, pricing of profiles shifts from default to requiring alternative identity sources.
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Service providers see content but should not simultaneously see wallets.
A single deposit exchanges for an amount that cannot be matched later.
Withdrawals are still possible if the server goes down, meaning custody is considered on-chain.