Ethereum / EVM Address Checksum Validator (EIP-55)
指导
Ethereum / EVM Address Checksum Validator
Paste any Ethereum or EVM-compatible address and instantly check whether its mixed-case checksum is correct under EIP-55. The tool also returns the canonical checksummed form so you can copy a safe version back into your wallet, contract, or block explorer. Everything runs locally in your browser — no addresses are sent to a server.
如何使用
- Paste one or more 40-character hex addresses into the input box (one per line). The
0xprefix is optional. - Each row is validated as soon as you stop typing. The Status column tells you whether the checksum is Valid, Invalid, Unchecksummed, or Invalid format.
- The Checksummed column shows the correct EIP-55 mixed-case form. Click the copy icon to grab it.
- For unchecksummed or invalid inputs the case-flipped letters are highlighted so you can see exactly which characters were wrong.
特征
- EIP-55 validation – classifies each address as Valid, Invalid checksum, Unchecksummed (all-lower / all-upper / digits-only), or Invalid format.
- Canonical checksum output – every recognised address is shown in its correct mixed-case EIP-55 form, ready to copy.
- Batch input – paste a whole list of addresses and validate them at once. Each row is processed independently.
- Character-level diff – when the input does not match the checksum, the letters that need to change case are highlighted in the output.
- Zero-address detection – flags
0x0000...0000as the canonical burn / null address. - Chain-agnostic – the same 20-byte address format is used on Ethereum, Polygon, BSC, Arbitrum, Optimism, Base, Avalanche C-Chain and every other EVM-compatible network.
- 100% 客户端 – Keccak-256 runs in your browser via a hashing library; addresses are never transmitted off your machine.
何时使用
- Before sending a transaction to a freshly pasted address, to confirm that no character was mistyped.
- While writing smart contracts or scripts that hard-code addresses, to make sure each one is stored in checksummed form.
- When reviewing pull requests, audit reports, or KYC documents that contain a long list of addresses.
- When importing an address from an unchecksummed source (block explorer, CSV, log file) and you want the wallet-safe representation.
常问问题
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What exactly is an EIP-55 checksum?
EIP-55 is an Ethereum Improvement Proposal that adds a checksum to the standard 40-character hex address by encoding extra information in the case of its letters. The address itself stays the same 20 bytes; the upper- or lower-case of each a–f letter is derived from the Keccak-256 hash of the lowercase address. A wallet that understands EIP-55 can reject any address whose case-pattern does not match, catching most typos at the user-interface layer.
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How is the checksum computed?
Take the address without the 0x prefix and convert it to lowercase. Compute the Keccak-256 hash of those 40 ASCII characters. For each position 0–39, look at the corresponding hex nibble of the hash: if it is greater than or equal to 8, the address character at that position is upper-cased (if it is a letter); otherwise it stays lower-case. Digits are unaffected. The result is the canonical mixed-case address.
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Is Keccak-256 the same as SHA3-256?
No. Keccak-256 is the original Keccak submission to the NIST SHA-3 competition. NIST then standardised a slightly modified version of Keccak as FIPS-202 SHA3-256 by changing the padding rule. The two functions produce different digests for the same input. Ethereum and EIP-55 use the original Keccak-256, not the standardised SHA3-256.
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What does Unchecksummed mean?
An address whose letters are all lowercase or all uppercase carries no checksum information. It is still a valid 20-byte identifier and most EVM nodes will accept it, but a wallet that supports EIP-55 cannot use it to detect typos. The tool flags these inputs so you can replace them with the mixed-case version.
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Does the checksum vary between chains?
Plain EIP-55 does not depend on the chain — the same lowercase address always produces the same mixed-case result. A later proposal, EIP-1191, introduces chain-id-aware checksums but it never became universally adopted. The vast majority of wallets and explorers (MetaMask, Etherscan, Polygonscan, etc.) implement plain EIP-55, which is what this tool validates.
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Can a checksum guarantee that an address controls funds?
No. A valid EIP-55 checksum only proves that the 20 bytes form a syntactically well-formed identifier and that the mixed-case pattern is internally consistent. It says nothing about whether anyone holds the private key, whether the address is a contract or an EOA, or whether it has any balance. Always check ownership and on-chain history separately before sending value.
