Sign EIP-2612 Permit

WHAT IT DOES

Sign EIP-2612 Permit enables you to create signed approvals for ERC-20 token spending using the EIP-2612 permit standard. Instead of submitting an on-chain approve() transaction that costs gas, you can sign a structured message that authorizes a spender to use your tokens. This gasless approval mechanism allows users to approve token spending without paying gas fees, enabling better user experiences in DeFi applications where users may not have native tokens for gas. The tool reads your connected wallet address to determine the token owner, uses the current chain ID for domain separation, fetches token information including name, version, and current nonce from the token contract, and lets you specify the spender address, amount, and deadline. It constructs the complete EIP-2612 permit structure, displays a review of all parameters, and initiates a signature request through your wallet. After signing, the tool displays the full signature, which can be submitted to the token contract's permit() function by anyone to execute the approval.

HOW TO USE

Connect your wallet using the BGWallet connector. The tool automatically detects your current network. Enter the token contract address that supports EIP-2612 (e.g., DAI, USDC, UNI, or other permit-enabled tokens). Enter the spender address that you want to approve—this is typically a DeFi protocol, DEX, or dApp that needs permission to spend your tokens. Specify the amount to approve in the token's smallest unit (e.g., wei for 18-decimal tokens). The tool fetches the current nonce from the token contract to ensure the permit is valid and prevent replay attacks. Optionally, set a deadline timestamp (in seconds) after which the permit expires; if left at 0, the permit will not expire. The review panel displays the owner, token, spender, amount, nonce, and deadline for verification. After reviewing, click "Sign permit" to initiate the signature request in your wallet. The wallet will display the structured permit message for human-readable verification. Once signed, the tool displays the full signature, which you can copy and provide to the spender or submit to the token contract.

TECHNICAL MECHANISM

This tool implements the EIP-2612 permit standard for gasless approvals. It constructs an EIP-712 typed data structure following the Permit type specification, which includes the owner, spender, value (amount), nonce, and deadline. The tool fetches the token's name, version, and current nonce for the owner from the token contract using the standard ERC-2612 interface. The nonce is incremented by the token contract each time a permit is successfully executed, preventing replay attacks. The domain object includes the token name, version, chain ID, and the token contract address as the verifying contract, ensuring the signature is valid only for that specific token and chain. The tool then uses the wallet's _signTypedData() function to sign the structured data, producing an EIP-712-compliant signature. The resulting signature (v, r, s components) can be passed to the token's permit() function, which verifies the signature against the stored nonce and the signer's address, then updates the allowance mapping to grant the spender the approved amount. The permit is gasless for the user, but the party that submits the permit pays the gas for the execution transaction.

WHAT IT CANNOT SEE

This tool cannot verify that the signed permit will be accepted or executed by the token contract without additional testing—you must ensure that the token contract implements EIP-2612 correctly and that your signature matches the expected format. It does not validate that the token contract implements EIP-2612 properly or that the permit function behaves as expected. The tool cannot recover or modify the signature once signed; you must verify the permit parameters carefully before approving. It does not automatically submit the permit signature to any contract—you must provide the signature to the spender or submit it to the token contract yourself. The tool cannot guarantee that the token contract supports the permit function; many older or custom ERC-20 tokens do not implement EIP-2612. It does not check if the token's permit implementation matches the standard or if there are any deviations that could cause the signature to fail. The tool cannot guarantee that the spender will execute the permit in a timely manner before the deadline expires; if the deadline passes, the permit becomes invalid.

PLEASE NOTE

This tool works only with ERC-20 tokens that implement the EIP-2612 permit standard. Not all ERC-20 tokens support permit; check the token's documentation or contract code to verify compatibility. The token contract address must be correct and the token must be deployed on the same network as your connected wallet. The amount should be specified in the token's smallest unit (e.g., 1 DAI with 18 decimals is 1000000000000000000). The deadline is a Unix timestamp; if set to 0, the permit never expires, but this is generally not recommended for security reasons. The signature must be submitted to the token contract's permit() function by the spender or any third party within the deadline. Always verify the spender address before signing—it will have permission to spend the specified amount of your tokens. After signing, the signature is cryptographically bound to the owner address, token contract, amount, nonce, and deadline, preventing misuse or replay on other chains.