What-Happens-If-I-Sign Simulator

WHAT IT DOES

What-Happens-If-I-Sign Simulator takes any transaction and tells you exactly what would happen if you sign it. It decodes the function signature, extracts and explains every parameter, runs a dry-run simulation via eth_call to see if the transaction would succeed or fail, analyzes the recipient to determine if it's an EOA or contract, and flags suspicious patterns. The AI translates all of this into a clear, plain-English explanation of what the transaction would accomplish, whether it would work, what the real-world consequences are, and what assets or permissions would be affected. All before your wallet ever asks for a signature—so you know exactly what you're getting into.

HOW TO USE

Connect your EVM wallet using the BotGentz wallet bridge. Select the network matching your transaction. Paste a transaction hash to fetch and simulate the full transaction, or paste raw hex call data to simulate directly. Click "What happens if I sign?"—the tool decodes the function, simulates the transaction, analyzes the recipient, flags risks, and generates an AI explanation. Results show you the simulation status (succeed/fail), revert reason (if any), sender, recipient (with EOA/contract badge), value, function name, decoded parameters, risk flags, and a clear plain-English explanation of what would happen. No transaction is ever submitted—this tool is read-only and free.

TECHNICAL MECHANISM

The app uses the injected BGWallet bridge to access the EVM provider via ethers.js v5.7.2. Transaction hashes are fetched via provider.getTransaction(). Call data is decoded against a built-in 4-byte signature database covering common functions (ERC20 transfer/approve, ERC721 safeTransferFrom, mint, owner, transferOwnership, pause, withdraw, selfdestruct, and more). Parameter decoding extracts addresses (padded to 64 hex chars), uint256 values, and booleans. A dry-run simulation is performed using provider.call() with the transaction data, capturing revert reasons if the call fails. Recipient bytecode is fetched via provider.getCode() to determine if the recipient is an EOA (no code) or a contract (code present). Risk flags are generated based on the decoded function, parameters, and value—unlimited approvals, ownership changes, self-destruct, large transfers, and withdraw functions. The AI bridge (BGAI.generate) receives a comprehensive prompt with the decoded data, simulation results, recipient analysis, flags, and risk level, and returns a plain-English explanation capped at 1,024 tokens.

WHAT IT CANNOT SEE

This tool cannot guarantee that simulation results match actual execution—state can change between simulation and submission. It cannot detect malicious intent hidden in contract bytecode—it reads only the function call data visible on-chain. It cannot verify that the resolved function name from the signature database matches the actual contract implementation—any contract can implement a function with the same method ID but completely different behavior. It cannot verify off-chain intent or consequences. It cannot detect cross-contract exploits, reentrancy vulnerabilities, or front-running attempts. The AI explanation is generated from the provided data and may miss nuanced attack patterns not present in the call data itself.

PLEASE NOTE

Supports EVM-compatible chains only—Ethereum, Sepolia, Polygon, Mumbai, Optimism, Arbitrum, and any network the wallet bridge connects to. The signature database is built-in and covers the most common functions—if a function is not in the database, the tool will show the method ID and raw data but cannot provide a function name. Simulations are estimates based on current state. Explanations are AI-generated and should be treated as assists, not authoritative guarantees. Always review the transaction details in your wallet's own signature prompt before approving. The wallet's signature step is the only protection that actually gates any action—this tool is informational and does not replace that safeguard. Free to use, no API keys required.