Ethereum Foundation launches zkAPI for prepaid API access

The Ethereum Foundation and Open Anonymity Project have launched zkAPI on Ethereum mainnet, a system designed to let users prepay for AI and other metered API services without directly connecting payment credentials to their requests. The project’s descriptions say it separates billing from prompts, but it does not conceal users’ network information or identifying details they include in those prompts. Users deposit funds, including ETH or USDC, into an Ethereum vault. According to the project’s documentation, software on a user’s device then generates a zero-knowledge proof to authorize spending without revealing which deposit backs the request. A server verifies the proof and issues a temporary API key with a spending limit. Prompts are sent directly to the AI provider, while the payment is settled separately through the system. The design is intended to reduce the connection between a user’s payment account and their API activity. Under conventional arrangements, an API key may be associated with an account and payment method, potentially allowing providers to associate usage with a persistent identity.