✅ EIP-55 Ethereum Address Checksum
Check whether an Ethereum address has a valid EIP-55 checksum, and convert any address to its correct mixed-case form, the standard way wallets catch mistyped addresses.
Checksummed (EIP-55)
0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed
EIP-55 encodes a checksum in the letter casing of a hex address, each letter is uppercased when the matching nibble of the address’s Keccak-256 hash is ≥ 8. Wallets use it to catch typos. This validates and converts any address, entirely in your browser. Public addresses only, never paste a private key or seed phrase anywhere.
How the eip-55 ethereum address checksum works
EIP-55 hides a checksum in the letter casing of a hex address: the tool takes the lowercase 40-hex-digit address (without the 0x), computes its Keccak-256 hash, and for each alphabetic character (a, f) uppercases it when the corresponding nibble of that hash is 8 or greater, leaving it lowercase otherwise. Digits 0-9 have no case and are unaffected. Paste an address and the tool tells you whether its casing is a valid checksum (a strong signal it wasn’t mistyped) and gives you the correctly-checksummed version to copy.
A safety-oriented developer utility for PUBLIC addresses only. It never handles private keys, seed phrases or funds, performs no transactions, and gives no financial advice, never paste a private key or seed phrase into any tool.
Frequently asked questions
What is an EIP-55 checksum?
A way of encoding a checksum into the upper/lowercase pattern of an Ethereum address’s hex letters, defined in EIP-55. A wallet can then detect a single mistyped character, because the casing would no longer match the address’s Keccak-256 hash.
How do I know if an address is valid?
Paste it here: if the mixed-case matches EIP-55, it’s a valid checksum (unlikely to be mistyped). An all-lowercase or all-uppercase address has no checksum to verify. This tool will give you the correct checksummed form.
Does a valid checksum mean the address is “safe”?
It only means the address is well-formed and probably not mistyped. It says nothing about who controls the address or whether it’s trustworthy, always verify the recipient through a trusted channel.
Why are some letters uppercase?
Each hex letter (a, f) is uppercased when the matching nibble of the address’s Keccak-256 hash is ≥ 8. That pattern is the checksum; digits (0-9) are unaffected.
How many characters is an Ethereum address?
Forty hexadecimal digits (20 bytes), conventionally shown with a 0x prefix for 42 characters in total. EIP-55 doesn’t change the address itself. It only sets the upper/lowercase pattern of the letters a, f within those 40 digits.
Will a wrong-case address still work on-chain?
An all-lowercase address is accepted everywhere because it carries no checksum to fail. A mixed-case address that violates EIP-55, however, is rejected by most wallets and libraries as invalid, which is the whole point: it catches a typo before funds are sent. Use the checksummed form this tool outputs.
Do you ever handle private keys?
Never. This works only with public addresses, entirely in your browser. Do not paste a private key or seed phrase into this or any online tool.