> ethereum | eip-55 | validator <
// Verify EIP-55 mixed-case Ethereum address checksums and convert any address to its canonical form
EIP-55 Verification
Recomputes the keccak256 hash of the lowercase address and compares each nibble to detect a single mistyped character before you sign a transaction.
Convert to Canonical Form
Paste any case (lowercase, uppercase, or mixed) and instantly normalize to the EIP-55 mixed-case form ready to paste into wallets, explorers, and contracts.
Client-Side Keccak-256
Keccak-256 runs locally via js-sha3. The address you paste is never transmitted, so even private treasury and multisig addresses are safe to validate offline.
// ABOUT EIP-55
How EIP-55 Works:
EIP-55, proposed by Vitalik Buterin in 2016, takes the lowercase 40-character address (without 0x), computes keccak256 of its ASCII bytes per the Ethereum Yellow Paper, and for each address character checks the matching nibble of the hash: if the nibble is at least 8 the character is uppercased, otherwise it stays lowercase. This produces a backwards-compatible checksum that catches roughly 99.986% of single-character typos.
Example:
0xfb6916095ca1df60bb79ce92ce3ea74c37c5d359 -> 0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359 (mixed-case is the EIP-55 checksum).
Common Use Cases:
- >Verify a copy-pasted address before signing a transaction
- >Normalize a lowercase address from logs into canonical EIP-55 form
- >Audit wallet UIs and dashboards that incorrectly downcase addresses
- >Detect single-character typos in receiver and contract addresses
- >Validate and normalize addresses inside CI/CD or migration scripts
>> frequently asked questions
Q: What is EIP-55?
A: EIP-55 is the 2016 Ethereum Improvement Proposal that introduced a mixed-case checksum for hex addresses, defined alongside the keccak256 primitive of the Ethereum Yellow Paper. It encodes roughly 5 bits of integrity per character without changing the address length, and is now supported by every major wallet, explorer, and SDK.
Q: My address is all lowercase - is it invalid?
A: No. A fully lowercase or fully uppercase address is technically valid (just unchecksummed). It still points at the correct account; the EIP-55 checksum simply cannot help spot a typo. This tool labels that case 'Lowercase only (no checksum)' and offers a one-click convert button to normalize the address into the canonical mixed-case form.
Q: Does this work for ENS names?
A: No. EIP-55 only applies to raw 0x-hex addresses. ENS names like vitalik.eth must be resolved to an address through the ENS registry first, which requires an RPC connection. This tool intentionally stays offline and does not perform any RPC lookups, so your validation remains fully client-side.
Q: What hash function is used?
A: Keccak-256 (the original pre-NIST Keccak as used throughout the Ethereum Yellow Paper, not SHA3-256). The two algorithms differ in their padding bytes: using SHA3-256 would produce a wrong checksum for every Ethereum address, so make sure your library or browser polyfill is keccak256, not sha3.
Q: Can EIP-55 catch every typo?
A: It catches the overwhelming majority but not 100%. For high-value transfers, also verify the first and last characters by eye, send a small test transaction first, and confirm the receiving address on-device using a hardware wallet. EIP-55 is a defense in depth, not a replacement for careful review.