Web3
Web3 utilities for builders
Wallet address checker (ENS, format, checksum), ETH ↔ Wei converter. Lightweight, no wallet connection required.
3 tools
- Wallet Address CheckerValidate Ethereum (EIP-55), Bitcoin (legacy/segwit/bech32), and Solana addresses. Browser-only, no blockchain queries.
- ETH ↔ Wei ↔ Gwei ConverterConvert between Ethereum units (wei, gwei, ether, etc.). BigInt math, no precision loss.
- BIP-39 Mnemonic ToolGenerate, validate and convert BIP-39 mnemonic phrases (12–24 words) — entropy, checksum and seed derivation, English wordlist. Runs in your browser, for learning and testing only.
Choosing between these tools
Two tools, both for the moment before you sign something: converting between ETH, Gwei and Wei, and checking that an address is what it claims to be.
Wei is the base unit and there are 10^18 of them in one ETH, which is why gas is quoted in Gwei — a billion Wei — and why a misplaced decimal in a manual transaction is expensive rather than merely embarrassing. The converter keeps full integer precision instead of routing the value through a floating-point number, so a balance stays exact at eighteen decimals.
The address checker validates the format and the EIP-55 mixed-case checksum, which is the cheap way to catch a character that was mistyped or altered in transit. It reads the address only; it does not connect a wallet, ask for a key, or broadcast anything. As with every tool here, the check runs in your browser.