Etheract

Etheract allows to easily interact with any Solidity or Vyper contract with a simple UI. No source code or ABI is needed.

Available for Ethereum, BSC, Polygon, Avalanche, Fantom, Goerli, Sepolia and custom chains.

How it works

Every Ethereum function is represented by its signature which corresponds to the first 4 bytes of the keccak256 hash of functionName(param1,param2,...) (e.g. the signature of function approve(address spender, uint256 amount) is 095ea7b3).

Going from the signature to the original function name and parameters is only possible by storing them in a lookup table (or database).

Jump table

Every contract's bytecode contains a jump table which tries to jump to a particular function depending on the signature. This is similar to a switch statement

e.g.

switch(signature) {
    case "095ea7b3": {
        //Jump to corresponding function
    }
    ...
}

Etheract finds function signatures by skimming through the jump table using regular expressions.

• Solidity function signatures are preceded by 8063 (DUP1, PUSH4) opcodes
• Vyper function signatures are contained between 005b63 and 600051141561 opcodes

These signatures are then matched to their corresponding function by querying the database, which can be parsed to find the parameters.

Signature database

• Ethereum Signature Database by samczsun