Permit signatures can remove a separate token approval

Permit signatures let a wallet authorize token spending off-chain, so a swap app can bundle that approval with the transaction that uses it. The wallet signs a message; a contract checks it when the swap is submitted, which can save a separate on-chain approval step.

The signature does not move tokens by itself. The submitted transaction still runs on-chain and pays a network fee, and the flow depends on the token and app supporting the relevant permit method. For a separate walkthrough of the route, see Quickswap first cross-chain swap steps.

How does a permit signature work?

A permit is a signed instruction that gives a specified contract permission to spend tokens under defined terms. With ERC-2612, a compatible token verifies the signature and updates its allowance when a contract calls its permit function; the app can include that call alongside the swap.

The message commonly specifies the token, spender, amount, nonce and deadline. Those fields limit what the signature authorizes and prevent reuse: a nonce tracks which permits have been used, while an expired deadline makes an old signature invalid. EIP-712 typed data helps wallets display structured signing requests, but the wallet prompt still needs careful review.

Does signing always remove the approval transaction?

No. A token must support a permit method, and the app’s route must be built to use it. If either does not, the wallet may still need to send a standard approval transaction before the swap.

Permit2 offers another pattern for supported integrations: the token is first approved to the Permit2 contract on-chain, then a user can sign a transfer authorization for a particular spend. That first approval remains a transaction; later signature-based transfers can avoid a new token approval each time. The gain is most useful after that setup, especially for repeated swaps.

What should users check before signing?

Read the wallet’s typed message and confirm which token, spender, amount and expiry it names. A signature is not a transaction, but it grants authority that a contract can use if the message is valid and unexpired.

• Check that the spender matches the app or router you intended to use.
• Prefer a specific amount and short expiry when the flow offers those choices.
• Reject a request whose token, chain or terms do not match the action on screen.

For most users, a permit is a useful way to combine authorization and a swap when the wallet and route support it. The practical check is whether the transaction preview shows the swap using the signature; otherwise, expect a separate approval before the swap can proceed.