The Ethereum Foundation and Open Anonymity Project launched zkAPI, a privacy-preserving payment layer for metered APIs that is now live on Ethereum mainnet. Users deposit ETH, USDC, or other credits into an onchain vault and authorize spending with zero-knowledge proofs, allowing providers to verify payment without learning the payer’s identity or which deposit funded the usage. zkAPI can issue short-lived, spending-capped API keys and settle based on actual usage. It is initially focused on AI inference but can extend to other pay-per-use services. The system does not provide network or content anonymity, meaning IP addresses, timing patterns, and identifying information in prompts may still be linkable.