Web3 — Ethereum address & hex key check

Client

Paste a 40-digit hex address (optional 0x) to validate EIP-55 checksums, or a 64-digit hex string to check private-key length and secp256k1 range. No chain access, no signing.

Sensitive data: processing stays in your browser, but avoid pasting real private keys or custodial secrets on shared machines. Private-key checks here are format and range only—no derivation, signing, or network calls.
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Paste one value: 40 hex digits (20-byte Ethereum address) or 64 hex digits (32-byte secp256k1 private key). Optional 0x prefix. Addresses get EIP-55 checksum validation when you use mixed case.

Result

Type: Ethereum address (20 bytes)

All lower or all upper hex—checksum not encoded. Correct EIP-55 form:

0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed

Common use cases

  • Verify a pasted 0x address before using it in a dApp config or test fixture.
  • Catch mixed-case address typos when EIP-55 does not match the lowercase hash rule.
  • Confirm a 64-digit hex string is in the valid scalar range before treating it as a key in documentation examples.

Common mistakes to avoid

  • Treating this as a wallet or signer

    The page does not derive addresses from keys, sign transactions, or call JSON-RPC—format only.

  • Sharing screenshots with private keys

    Even “test” keys can be swept if reused; blur or redact before posting.

FAQ

Is Base58 the same as an Ethereum address?

No. Ethereum public addresses are 20-byte hex with optional EIP-55 casing. Base58 (and Base58Check) are different encodings—use the Base58 tool for those strings.

Why does all-lowercase still show a checksummed line?

All lower or all upper hex is valid but does not embed a checksum. The tool shows the canonical EIP-55 form you can copy into strict APIs.

Do you store pasted keys?

No. Logic runs locally in the page; nothing is sent to Toolcore for this validator.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • ethereum address checksum validator online
  • eip 55 address check in browser
  • validate eth address 0x checksum
  • check secp256k1 private key hex format
  • ethereum private key length validator local

More tools

Related utilities you can open in another tab—mostly client-side.