what's Permit2?

Permit2 is an open-source smart contract protocol developed by Uniswap Labs to enhance ERC-20 token approvals in DeFi. It introduces features like time-bound (expiring) allowances to reduce risks from infinite approvals, gasless signatures via permits for reusable approvals across apps, and batch operations for approvals/revokes. This replaces traditional approve() calls with more secure, efficient mechanisms using SignatureTransfer and AllowanceTransfer contracts. By enabling shared approval management, universal permits for any ERC-20 token, and integration via SDKs, Permit2 minimizes user gas costs on repeated interactions and prevents exploits seen in hacks targeting unlimited allowances. It's non-upgradable, audited, and deployed on major chains, serving as public infrastructure for dApps.

Permit2 integrates with Titan Exchange via 0xProject for onchain settlement without standing approvals.