Ethereum’s zkAPI launches private API payments on mainnet

The Ethereum Foundation announced Thursday that zkAPI, developed with the Open Anonymity Project, is now live on Ethereum mainnet. The system is designed to let users pay for AI and other metered API services without directly linking requests to their billing identities.

Users deposit funds into an Ethereum vault and generate a cryptographic proof that they have enough credit to pay for an API request. The proof does not reveal which deposit belongs to the user, according to Vittorio Rivabella, an AI coordinator at the Ethereum Foundation’s dAI team.

zkAPI creates short-lived API keys with preset spending limits. Users send prompts directly to an AI provider, while payment for each request is processed separately through the zkAPI system. The project has released a local client, a software development kit and a browser-based AI chat application.

The system does not hide prompt content or network information from providers. IP addresses, request timing and details in prompts could still allow providers to link activity across sessions.

The mainnet launch follows a February proposal from Ethereum Foundation researcher Davide Crapis and Ethereum co-founder Vitalik Buterin for zero-knowledge-based credits for API use. The proposal described prepaid access to metered services without exposing a user’s payment history or identity to the provider.