zkAPI Mainnet Launch Tests User Financial Control

The Ethereum Foundation's implementation of zkAPI, a private AI-payment design co-authored by Vitalik Buterin and Davide Crapis, has been launched on mainnet. This gives users a concrete test of financial control: how to recover unspent money when the billing server stops cooperating.

zkAPI is a billing system for metered APIs that documents an on-chain withdrawal route without requiring server clearance. However, user ability to recover balance depends on spending state they hold and whether they can start an exit in time. The implementation's pause powers and expiring notes put boundaries around control.

The mainnet manifest specifies a challenge period of 24 hours for users to initiate an escape withdrawal without server clearance. If no valid challenge succeeds before the deadline, finalization pays the recorded balance to the user's destination and the deposit-minus-balance share to the treasury, provided transfers succeed.