The Ethereum Foundation has launched zkAPI on its main network, a system designed to enable private payments for AI services. The protocol allows users to deposit funds like ETH or USDC into a vault contract, converting them into private notes that cannot be traced back to the original transaction.
To use the service, a device generates a zero-knowledge proof verifying sufficient funds without revealing user identity. The server validates this proof and issues a temporary, memory-resident API key. This key grants access to AI providers without exposing personal data or payment details.
The system was developed in collaboration with the Open Anonymity Project and includes the browser-based OA Chat. The protocol is currently compatible with OpenRouter, allowing integration for any application that supports the OpenAI format.
The concept originated from a February proposal by Davide Crapis and Vitalik Buterin. Crapis, who leads the foundation's dAI team, previously co-authored the ERC-8004 standard in August 2025 to facilitate transactions between autonomous AI agents.
While the protocol aims to secure user prompts sent to cloud servers, the project documentation explicitly labels the current implementation as experimental. It notes that the code has not undergone a formal security audit.
