Ethereum Foundation launches zkAPI for private AI payments

The Ethereum Foundation launched zkAPI on Ethereum mainnet on Oct. 1 with the Open Anonymity Project, letting users pay for AI and other metered APIs without linking payments to their identity, according to the Foundation’s announcement.

How does zkAPI separate payment from identity?

Users deposit funds such as ETH or USDC into an Ethereum vault, where the balance is represented as a private note. Their device generates a zero-knowledge proof that the note can cover a payment without revealing which deposit funded it, the Foundation said.

The zkAPI server verifies the proof and issues a temporary API key with a spending cap. The user sends prompts directly to the AI provider, and when the key expires, the server deducts the measured usage from the private balance. The Foundation says a single authorization can cover a session rather than requiring a proof for each request.

What can the provider and payment server see?

The provider receives prompts and responses, while the payment server sees the spend; the system is designed to keep either side from linking the request to the user’s billing identity. The Block’s report on the launch describes the same flow and says the client supports existing OpenAI- and Ollama-compatible tools.

The Foundation says zkAPI can also support metered services such as blockchain RPC, image and video generation, VPN bandwidth and machine-to-machine payments. It implements “ZK API Usage Credits,” a design published on Ethereum Research by Ethereum Foundation dAI lead Davide Crapis and co-founder Vitalik Buterin.

What privacy limits remain?

zkAPI does not hide a user’s IP address, prompt contents or other network metadata from the provider. The Foundation says a stable IP address, request timing, personal details or reused conversation history could allow sessions to be correlated.

The Foundation says the system is live on mainnet, with a local gateway and browser chat available. Users can try the service now, while providers can integrate it by accepting proofs and settling signed usage receipts.

References

• Foundation’s announcement — blog.ethereum.org
• Block’s report on the launch — theblock.co