Ethereum Address Validator: Format Plus the EIP-55 Checksum
Case looks cosmetic in most addresses. In Ethereum it is the checksum, and this validator reads it properly.
What is the Ethereum Address Validator?
An Ethereum address is 0x followed by 40 hexadecimal characters, and the EIP-55 standard adds a checksum by capitalising certain letters according to a Keccak-256 hash of the lowercase address. This validator first checks the format, then recomputes that mixed-case form with a self-contained Keccak-256 implementation and compares it letter by letter. An all-lowercase address passes the format check but is reported as not checksummed, because its capitalisation carries no checksum.
How to use it
- Paste the Ethereum address, including the 0x prefix.
- Click Validate Address.
- If it is all lowercase, note that the format passes but the checksum is absent.
- Use the checksummed form shown when a checksummed address is needed.
Worked example
Validating the EIP-55 example address reports it as valid and checksummed, while its all-lowercase form is flagged as not checksummed.
Is 0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed checksummed?
Yes. Its mixed-case letters match the EIP-55 form derived from the Keccak-256 hash of the lowercase address, so it validates as a checksummed address.
Frequently asked questions
Why does capitalisation matter in an Ethereum address?
EIP-55 turns capitalisation into a checksum: each letter is uppercased only when the matching hash nibble is eight or higher.
Is an all-lowercase address unusable?
No. Wallets accept it, but it carries no checksum protection, so a typo in it would not be caught by this check.