--- title: "Ethereum Foundation and Open Anonymity Project Deploy zkAPI on Mainnet" description: "The protocol uses zero-knowledge proofs to let users pay for metered AI queries and APIs without linking requests to their billing identities." url: https://basisdesk.news/news/ethereum-foundation-deploys-zkapi-mainnet published: 2026-10-01T19:12:10.355Z modified: 2026-10-01T19:12:10.355Z section: Tech & Protocols author: Basis Desk Newsroom (AI-generated, source-verified) sentiment: neutral tickers: [ETH, USDC] tags: [zk-proofs, ethereum-foundation, ai, privacy, developer-tools] license: Quote with attribution to Basis Desk (basisdesk.news). Not financial advice. --- # Ethereum Foundation and Open Anonymity Project Deploy zkAPI on Mainnet The protocol uses zero-knowledge proofs to let users pay for metered AI queries and APIs without linking requests to their billing identities. ## Key points - The Ethereum Foundation and Open Anonymity Project launched zkAPI on Ethereum mainnet on Oct. 1 [1]. - Users deposit funds into an onchain vault, authorizing metered sessions via Groth16 zero-knowledge proofs without exposing billing accounts [1]. - The system shields payment identities for AI queries and RPCs, though network-level and prompt-content tracking require external mitigations [1]. ## Editorial remark - **Context:** Commercial AI application interfaces systematically bind prompts to billing identities, creating persistent logs linking individual payment cards to sensitive queries. zkAPI adapts research by Davide Crapis and Vitalik Buterin to decouple onchain balances from application usage. - **Impact:** Developers and automated onchain agents can query metered APIs without maintaining centralized billing accounts. AI inference providers can accept signed usage receipts for settlement without handling custody or personally identifiable financial records. - **Watch:** Monitor developer integration rates of the local client across OpenAI-compatible applications, alongside third-party service provider support for zkAPI usage receipts and mainnet vault total value locked. The Ethereum Foundation and the Open Anonymity Project have launched zkAPI on Ethereum mainnet, introducing a protocol that allows users to pay for metered API access without exposing their identities to service providers [1]. The release implements an earlier design co-authored by Davide Crapis and Ethereum co-founder Vitalik Buterin [1]. Under current web architecture, metered API services such as AI inference require users to provide API keys tied directly to corporate accounts and payment methods [1]. zkAPI alters this flow by splitting payment settlements from usage data [1]. Users deposit assets like $ETH or $USDC into an onchain vault contract, creating an offchain balance represented as a private note [1]. To fund API calls, a local client generates Groth16 zero-knowledge proofs on the BN254 curve, proving that a funded, unspent note exists within a 32-level Merkle tree [1]. The zkAPI server verifies these spend proofs offchain and provisions short-lived, dollar-capped API keys directly to the client's memory [1]. ## Cryptographic Isolation and Limitations Once authorized, client requests travel directly to the API provider using the ephemeral key [1]. When a key expires, the provider issues a signed usage receipt, prompting the zkAPI server to deduct the exact metered amount rather than the initial spending cap [1]. Because nullifiers prevent double-spending and commitments mask the funding origin, providers observe user prompts but cannot identify the payer, while payment servers record metered charges without accessing request contents [1]. If intermediary servers go offline, depositors retain the ability to exit and recover their remaining funds directly from the onchain vault contract [1]. At the time of writing, ETH traded at $2,705. The developers noted that zkAPI addresses billing links but does not provide complete anonymity [1]. API providers still process raw prompt contents and IP addresses, meaning users must employ network protections like Tor or confidential computing environments to prevent traffic correlation or content-based fingerprinting [1]. Beyond AI inference, the project stated that the system is designed to support private metered billing for blockchain RPC nodes, image generation, machine-to-machine agent tasks, and VPN bandwidth [1]. ## FAQ **Does zkAPI hide prompt contents from AI providers?** No. The AI provider still processes the prompt to generate an answer. zkAPI only breaks the link between the user's billing identity and the API requests. **Can zkAPI servers withhold user funds?** No. Deposits sit in an onchain Ethereum vault contract, allowing depositors to close their balances and withdraw onchain even if the server becomes unavailable. ## Sources 1. [Introducing zkAPI: private usage credits for any API](https://blog.ethereum.org/en/2026/10/01/introducing-zkapi) — Ethereum Foundation Blog, 2026-10-01 --- Basis Desk Newsroom · AI-generated, source-verified · https://basisdesk.news/about/how-we-use-ai