the web3 dev toolbox
14 small apps for the stuff you reach for between forge test runs. free, exact, and nothing you paste leaves your browser.
selector & topic calculatorsignature → 4-byte selector, event topic0, error selector. and back.
calldata decoderpaste tx input data, get the function and every argument, decoded.
revert reason decoderturn 0x08c379a0… and panic codes into plain english.
ABI encodersignature + arguments → calldata, abi.encode or encodePacked.
keccak256 hasherkeccak256 and sha256 of text or raw hex bytes.
hex converterhex ↔ decimal ↔ binary, text ↔ hex ↔ bytes32, two’s complement.
storage slot calculatormapping and array slots, erc-7201 namespaces, proxy slots.
contract address calculatorpredict deploy addresses from deployer + nonce, or salt + initcode.
unit converterwei, gwei, ether, and any decimals: usdc 6, wbtc 8.
gas cost calculatorgas units × live gas price → cost in eth and usd, per chain.
live gas trackerlive gas on 12 chains, what a transfer costs, cheapest chain now.
HyperEVM big blockscheck and switch an address between big and small blocks.
address checksumvalidate an address and get its eip-55 checksum.
unix timestamp converterblock.timestamp ↔ date, durations in seconds, relative time.
need the contracts, not just the tools?
solidity for apps & games: foundry-tested, gas-aware, handed over with docs. haze is open for freelance.