Hidden Fee Function Detector

WHAT IT DOES

Hidden Fee Function Detector reads live on-chain bytecode from any EVM token contract and uses AI to detect hidden fees, transfer taxes, and abusive tokenomics that extract value from traders. It examines the transfer function implementation for balance before/after checks, fee-on-transfer patterns, and tax calculation logic. It detects fee control functions like setFee(), setBuyFee(), setSellFee(), and setFeeReceiver() that indicate dynamic fee structures. It identifies blacklist/whitelist exemptions that allow certain addresses to avoid fees. It detects anti-whale mechanics like max transaction limits and max wallet holdings that can trap sellers. It scans for reflection/redistribution patterns and rebase triggers. The AI generates a plain-language verdict—SAFE, RISKY, or CRITICAL—along with specific explanations of the fee risks before you buy, sell, or hold the token.

HOW TO USE

Paste any EVM token contract address into the input field. The tool reads the contract's bytecode and scans for known fee-related function signatures using 4-byte method identifiers—setFee() (0x53cf1536), setBuyFee() (0x8f59485e), setSellFee() (0x8b2c78e4), setBlacklist() (0x5ae6a9e1), withdrawFees() (0x2e1a7d4d), setFeeReceiver() (0x51cff8d9), setMaxTx() (0xd5a06d4c), and setMaxWallet() (0xeb7967d0). It also scans for bytecode patterns indicating fee-on-transfer (balance comparison before/after transfer), fee percentage calculation (multiplication/division operations), blacklist/whitelist mappings, and buy/sell tax disparities. The AI receives all this data and returns a verdict: SAFE (no fee functions detected), RISKY (fee functions exist but potentially documented), or CRITICAL (multiple fee extraction mechanisms, hidden taxes, or owner-controlled exemptions). The AI also provides a detailed plain-language explanation of the specific fee risks.

BYTECODE PATTERN ANALYSIS AND SIGNATURE DETECTION

The tool scans the contract's bytecode for known function signatures using 4-byte method identifiers extracted from the first four bytes of calldata. This detects fee control functions even when source code is not verified. It also analyzes the raw bytecode for common fee-on-transfer patterns: balance checks before and after transfer using SLOAD and SUB opcodes, fee percentage calculations using MUL and DIV with constants like 100 (0x64) or 10000 (0x2710), mapping operations for blacklist/whitelist exemptions, and anti-whale limit checks. It identifies reflection/rebasing patterns through balance tracking relative to total supply. The tool does not require executing a transaction to detect these patterns; it reads the deployed bytecode directly from the chain. It automatically handles obfuscated code by focusing on opcode sequences rather than source-level readability. If a fee function signature is present, it flags the contract as having fee control capability, and if multiple fee-related patterns coexist, it elevates the risk level.

WHAT IT CANNOT SEE

This tool cannot detect off-chain fee claims not reflected in the bytecode—a contract could have no fee functions in bytecode but the team could charge fees through a separate mechanism. It cannot analyze bytecode that is obfuscated beyond EVM disassembly limits; some contracts use anti-analysis techniques that hide true behavior. It cannot verify if fees are actually charged in practice without executing transactions; a contract could have fee logic that is never activated. It cannot detect fees that are not embedded in the transfer function but applied through hooks, callbacks, or external contracts. It cannot detect fee disparities that depend on transaction origin beyond standard analysis. It cannot see pending fee changes not yet executed on-chain. It cannot verify if a fee setter function is protected by timelock or can be changed instantly.

PLEASE NOTE

EVM chains only. This tool reads on-chain data and generates AI explanations—it does NOT sign transactions or execute any on-chain actions. The wallet's own signature prompt remains the final gate for every real action. Always review the exact transaction details in your wallet before approving any token purchase, sale, or approval. The AI assessment is informational only and does not constitute financial or security advice. Always verify fee details independently through block explorers and official project documentation before assuming any token is safe to trade.