Permit2 & Signature Approvals

The Problem With Old Approvals

To let a DeFi app move your ERC-20 tokens, you have to grant it an approval. Traditionally this meant a separate on-chain transaction (costing gas) for each token and app, and apps often requested an unlimited approval so you would not have to re-approve. The result was clunky (an extra transaction before every first interaction) and dangerous (endless standing unlimited allowances that a future exploit could drain). Permit2 and the EIP-2612 permit standard were created to fix both problems.

Sign Instead of Transact

The core idea is to replace an on-chain approval transaction with a signed message. Instead of sending a gas-costing approval, you sign an off-chain permission that the app submits alongside the actual action. EIP-2612 adds this 'permit' capability to individual tokens; Permit2, a contract from Uniswap, brings it to tokens that do not natively support permits, and adds powerful features like a single approval that many apps can share, time-limited allowances that auto-expire, and batched permissions. For users this means fewer transactions, lower gas, and — crucially — approvals that can be scoped and made to expire.

• Old approvals were a separate gas-costing transaction, often for unlimited amounts
• Permit2 / EIP-2612 let you sign an off-chain message instead
• Permit2 adds shared approvals, time-limited allowances, and batching
• Fewer transactions, lower gas, and approvals that can expire