Ethereum Address Validator — Validate ETH Address & EIP-55 Checksum
Validate Ethereum addresses and verify or generate the EIP-55 mixed-case checksum in your browser. Detects format errors, shows the correctly checksummed address, and flags checksum mismatches. Uses a client-side keccak-256 implementation — your address never leaves your device.
How to use this tool
- Paste or type an Ethereum address in the input field.
- The tool checks the format and calculates the EIP-55 checksum in your browser.
- See the correctly checksummed address and whether the input matches.
About Ethereum Address Validator
The Ethereum Address Validator checks whether a string is a structurally valid Ethereum address and, when it contains mixed-case letters, verifies its EIP-55 checksum. A valid address is the literal text "0x" followed by exactly 40 hexadecimal characters, which corresponds to the 20-byte account identifier used on Ethereum and every EVM-compatible chain such as Polygon, Arbitrum, Optimism, and BNB Chain. Paste an address into the box and the result updates instantly: a green Valid badge or a red Invalid badge, the reason for any rejection, and the correctly checksummed form of the address.
The checksum logic follows EIP-55 exactly. The tool lowercases the address, computes the keccak-256 hash of those hex characters, and then uppercases each letter whose corresponding hash nibble is 8 or greater. This mixed-case pattern is a built-in typo detector: change a single character and the expected capitalization no longer matches, so a wallet can refuse the transfer before funds move. The validator treats an all-lowercase or all-uppercase address as valid but flags it as not checksummed, because those forms carry no error-detection information. A mixed-case address whose capitalization does not match the computed checksum is reported as an EIP-55 checksum mismatch and marked invalid.
Typical uses include sanity-checking an address copied from an email, block explorer, or spreadsheet before sending funds, converting a lowercase address into its canonical checksummed form for documentation, and confirming that an address pasted from an untrusted source has not been altered. The Copy button puts the checksummed version on your clipboard. Validation runs entirely in your browser, so the address you paste never leaves your device.
The tool validates format and checksum only. It cannot tell you whether an address is funded, whether it belongs to a contract or an externally owned account, whether it is a known scam address, or whether the recipient controls the private key. It also does not detect addresses that are valid in form but were generated incorrectly, and it does not confirm that an address is the one your counterparty actually intended to share. Always confirm the destination through a trusted channel before sending a transaction, because Ethereum transfers are irreversible and no central authority can reverse a payment sent to the wrong account.
Frequently Asked Questions
- What makes an Ethereum address valid?
- A valid Ethereum address is the prefix "0x" followed by exactly 40 hexadecimal characters (0-9 and a-f), representing a 20-byte value. Anything shorter, longer, or containing non-hex characters is rejected. This tool checks that format first and only then evaluates the checksum.
- What is the EIP-55 checksum?
- EIP-55 is a convention that encodes a checksum into an address by selectively capitalizing its hex letters. The address is hashed with keccak-256, and each letter is uppercased when the matching hash nibble is 8 or higher. Wallets compare the capitalization pattern of a typed address against this computed pattern to catch typos before sending funds.
- Is an all-lowercase address still valid?
- Yes. An all-lowercase or all-uppercase address is accepted as valid because it represents the same 20-byte value. However, it carries no checksum protection, so the tool flags it as "not checksummed" and shows the proper mixed-case version you can copy and use instead.
- Why does a mixed-case address get marked invalid?
- If an address uses mixed upper and lower case but the capitalization does not match the EIP-55 pattern computed from its keccak-256 hash, it is reported as a checksum mismatch. This usually means a character was mistyped or corrupted during copying, and the tool rejects it to prevent sending funds to the wrong account.
- Does this work for Polygon, Arbitrum, and other EVM chains?
- Yes. EVM-compatible networks share the same 20-byte address format and the same EIP-55 checksum scheme as Ethereum, so a valid Ethereum address is also a valid address on those chains. The same account can hold balances on multiple EVM networks, but this tool only checks the address string, not which network you intend to use.
- Can the tool tell me if an address has a balance or belongs to a contract?
- No. It checks format and checksum only. It does not connect to any blockchain, so it cannot report balances, transaction history, or whether the address is a smart contract or an externally owned account. For that information, look the address up on a block explorer.
- Does my address leave my browser?
- No. The keccak-256 hashing and all checksum logic run locally in your browser using JavaScript. The address you paste is never sent to a server, and the tool makes no network requests during validation.
Embed this tool on your site
Free. One line of HTML — the tool runs in your visitor's browser, no data sent to anyone.
<iframe src="https://brevio.pro/embed/ethereum-address-validator" width="100%" height="600" loading="lazy" style="border:1px solid #e5e5e5;border-radius:8px" title="Ethereum Address Validator — brevio"></iframe> <p style="font:12px/1.4 sans-serif"><a href="https://brevio.pro/tools/ethereum-address-validator">Ethereum Address Validator</a> by <a href="https://brevio.pro">brevio</a></p>