Permit2

Permit2 is a token approval protocol developed by Uniswap. It replaces the standard ERC-20 approve pattern with signature-based permissions that include expiration deadlines.

The Problem With Standard Approvals

With standard ERC-20 approvals:

• Contracts get access to your full approved amount, often unlimited
• Approvals never expire - they persist until you manually revoke them
• You're responsible for tracking and revoking every single one
• If a contract is compromised, those approvals can be drained

This is how $493M has been stolen since 2020.

How Permit2 Fixes This

With Permit2:

• You approve the Permit2 contract once per token (audited, non-upgradable, battle-tested by Uniswap)
• Each swap gets permission for the exact amount only
• Permissions expire automatically after a deadline
• Nothing to revoke - unused permits become invalid on their own

How freaky.fi Uses Permit2

When a Permit2-enabled quote is selected:

1. You sign a permit message (off-chain, no gas cost)
2. The signature authorizes the aggregator's router to spend the exact swap amount
3. The permission includes a deadline after which it becomes invalid
4. The swap executes atomically with the permit

No residual approval remains after the swap completes.

Implementations

freaky.fi is progressively implementing Permit2 across all supported aggregators:

For aggregators without Permit2 support, freaky.fi uses exact approvals as a fallback.

References

• Uniswap Permit2 Announcement
• Permit2 GitHub Repository