The Ethereum Foundation has introduced zkAPI and deployed it on Ethereum mainnet, giving users and AI agents a way to pay API fees with onchain assets including ETH and USDC while reducing the risk that payment identities are directly linked to API usage records.
zkAPI was developed jointly by the Ethereum Foundation and the Open Anonymity Project. Under the setup, users first deposit assets into a vault smart contract on Ethereum. They then use zero-knowledge proofs to show they have enough balance to pay, without telling the payment server which specific deposit or wallet is behind the payment.
No onchain transaction for every AI call
zkAPI is not designed to send a transaction on Ethereum every time an AI model is called. Users deposit funds first, and the zero-knowledge proofs are then verified mainly offchain. Once the system confirms payment capacity, it generates an API key with limits on time and spending, and that key is used to call the model.
The structure is aimed in particular at AI agents. As described in the source, agents may eventually buy large amounts of data, model inference, image generation, or other API services on their own every day. Requiring a credit card, manual account setup, or an onchain transaction for each purchase would make that workflow inefficient.
zkAPI offers payment unlinkability, not full anonymity
The Ethereum Foundation says zkAPI is built around payment unlinkability rather than complete anonymity. AI model providers can still see the prompts submitted by users and the model outputs, and they may also obtain network information such as IP addresses.
The main privacy goal is narrower: making it harder for a service provider to directly determine which Ethereum payment address funded a given API call.
Ethereum is targeting AI agent payments
The foundation has identified the AI agent economy as an important direction. Alongside zkAPI, the Ethereum ecosystem is also advancing the x402 payment standard, which is intended to let AI agents buy APIs, data, and other digital services with stablecoins on a per-use basis.
The two efforts address different parts of the stack. x402 is about how to automate payments. zkAPI is about how to pay without tying identity to each usage record. In that framing, Ethereum is trying to position itself as the underlying settlement network for machine-to-machine payments between AI agents.
Still early-stage infrastructure
For now, zkAPI remains early infrastructure. The Ethereum Foundation has not released figures for actual user numbers, API payment volume, or related protocol revenue.
At this stage, the rollout is better viewed as a strategic move into the AI agent payments market, rather than evidence of large-scale new demand for ETH.