Lab — Web3 tool
Wallet Address Validator is a free online tool that checks whether an Ethereum wallet address is well-formed and whether its mixed-case checksum follows EIP-55 — so you can catch a typo before funds go to the wrong place, all computed locally in your browser.
Address to check
Nothing leaves this page: no lookup, no balance check, no network request. This checks the format only — it cannot tell you whether an address belongs to anyone.
Verdict
Validation runs on every keystroke.
Rule checks
EIP-55 turns an address's letter casing into a checksum. Take the lowercase hex address, hash it with Keccak-256, and capitalise each letter whose matching hash nibble is 8 or higher. A wallet that understands EIP-55 can then spot a mistyped letter: change one letter's case and the checksum no longer matches. All-lowercase or all-uppercase addresses are still valid addresses — they simply carry no checksum protection, so a typo in them is harder to catch. This page implements Keccak-256 directly, with no libraries and no network calls.