zkAPI: Ethereum Foundation Launches API Payment System Separating Identity
Written with artificial intelligence.
On October 1, zkAPI was launched by the Ethereum Foundation as a new payment system for APIs that disconnects identity from payment. This innovative approach allows service providers to process requests without linking them to user accounts or payment methods.
Introduction to zkAPI
The Ethereum Foundation introduced zkAPI on October 1, aiming to enhance privacy in API payments. This system enables users to pay for APIs, including AI services, using ETH while ensuring that the service provider cannot trace back payments to user identities.
How zkAPI Works
zkAPI operates by separating the API usage from the payment method. Users deposit funds, either in ETH or USDC, into a secure Ethereum vault. The balance in this vault turns into a private note that only the user can access. To make a payment, a software application generates a zero-knowledge proof, confirming the availability of funds without revealing any personal information.
1. Depositing Funds: Users deposit once into the Ethereum vault. 2. Generating Proofs: The application sends a proof of payment to the zkAPI server without sharing any identity information. 3. Receiving Temporary API Key: The server issues a short-term API key that is stored only in the user's device. 4. Transacting: The user can then make API requests using this key. Upon expiration, a signed receipt captures the actual consumption, and the server deducts the amount from the user’s private balance.
Security and Privacy Features
The zkAPI system utilizes advanced cryptographic techniques to ensure that the identity of the payer remains anonymous. It uses Groth16 proofs on the BN254 curve for off-chain verification and includes mechanisms to prevent double spending. Importantly, while the server can verify that a valid payment has occurred, it does not learn who made the payment or the contents of the API requests.
Limitations and Considerations
While zkAPI enhances privacy for API transactions, it does not anonymize IP addresses or the content of requests. Therefore, users are advised to use additional privacy measures, such as Tor, to further safeguard their identity during transactions. This system represents a significant step in the integration of zero-knowledge proofs in blockchain technology, evolving the original concepts discussed by Vitalik Buterin and Davide Crapis in early 2026 into a practical application on the Ethereum mainnet.