ACTUAL DEFI DEVELOPER PAIN · FREE OFFLINE DIAGNOSIS
Is your app mixing AllowanceTransfer and SignatureTransfer? Does your signed spender differ from the contract actually calling Permit2? Before debugging gas, compare the required fields and function names using private browser-local JSON checks.
No wallet, signing, RPC, onchain approval lookup, secrets, balances, transaction submission or third-party analytics. No payment is made by viewing, typing, or analyzing this page. Never paste private keys, signed messages, API tokens or personal data.
Load a fictional example or paste a nonsecret, unsigned JSON planning envelope. This tool reads declared caller, spender, token, transfer amount and expected chain; it cannot run the contract or decode a revert.
No signed data. No real wallet history. Examples are fictional. If unsure what to paste, use the buttons above.
No private signing key, wallet extension, gas, escrow or payment. The browser does not upload your pasted JSON.
Differences in method names, caller, spender, signed amount, expiry and chain are often more useful than a generic estimateGas error.
An unknown or unflagged field never implies a safe call. Check the actual ABI, EIP-712 hash, nonce state and revert separately.
Use permit(address owner, PermitSingle|PermitBatch, bytes signature), then a separate transferFrom. The signed spender should match the contract that later invokes transferFrom; a relayer may submit the original permit.
Use permitTransferFrom(permit, transferDetails, owner, signature). Signed permission includes token/amount, nonce and deadline; actual caller is incorporated in contract authorization, while transferDetails.to is supplied by the call.
The token's ERC-20 approval of the Permit2 contract differs from the spender's Permit2-level permission. A checkbox or copied JSON does not independently prove either live allowance.
We don't sign, broadcast, estimate gas, fetch allowance state, inspect deployed bytecode, recover a signature, decode custom errors or certify a protocol. Use a verified testnet/local fork for execution debugging.
This tool addresses a class of mistakes illustrated by a real public Uniswap Permit2 debugging question. No affiliation, endorsement, actual remediation result, paying user or verified signature is implied.
FREE LOCAL CHECKER
No account, wallet, token approval, key, API key or payment. For deeper EIP-712 declaration inspection also use the original SignScope free inspector.
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