Permit Signature Generator and Submitter

WHAT IT DOES

Permit Signature Generator and Submitter lets you create and submit ERC-2612 permit signatures for gasless token approvals in a single streamlined flow. Instead of calling approve() and paying gas for the approval transaction, you sign an off-chain EIP-712 message that authorizes a spender to use your tokens. The tool fetches the required token details—name, domain separator, and current nonce—then generates the permit signature using your wallet's signing capabilities. It then submits the permit on-chain via a multicall transaction, completing the approval process with minimal gas and without a separate approve() transaction.

HOW TO USE

Connect your EVM wallet and select the network. Enter the token contract address (must support ERC-2612 permit), the spender address, the approval amount in wei, and a deadline as a Unix timestamp. Click "Fetch token details" to read the token's name, nonce, and domain separator—this also confirms that the token supports the permit interface. Review the displayed details, then click "Sign & submit permit". Your wallet will prompt you to sign the EIP-712 permit message. After signing, the tool automatically submits the permit on-chain using a multicall batch. The status area shows the transaction hash and gas fee.

TECHNICAL MECHANISM

The tool follows the ERC-2612 standard, which defines a permit() function on tokens that accepts an owner, spender, value, deadline, and EIP-712 signature (v, r, s). It first reads the token's name, nonces(owner), and DOMAIN_SEPARATOR() from the contract. It then constructs the EIP-712 domain and typed data structures, matching the standard Permit type. Using your wallet's _signTypedData() method (EIP-712 signing), it generates the signature. The signature components (v, r, s) are then encoded into a permit() call and submitted on-chain via Multicall3 aggregate3(). This bundles the permit submission into a single transaction, reducing gas costs and streamlining the process.

WHAT IT CANNOT SEE

This tool cannot verify off-chain signature validity before on-chain submission—a permit may fail if the nonce is incorrect, the deadline has passed, or the token's domain separator has changed. It relies entirely on tokens supporting the ERC-2612 permit interface; tokens that do not implement permit() or use non-standard versions (e.g., DAI's permit) are not supported. The tool does not generate signatures without explicit user signing—each permit requires a wallet signature confirmation. It also cannot detect or handle standard approve() approvals; it only works with permit-based approvals.

PLEASE NOTE

The deadline must be a Unix timestamp in the future—ensure you set it far enough ahead to allow for signing and submission. The nonce is automatically read from the token contract; if you have previously used a permit for the same token, the nonce will have increased. The multicall contract address used is the standard Multicall3 address—verify it is deployed on your chosen network. This tool is for EVM chains only and does not support non-EVM networks.