How do I convert an Ethereum address to its checksummed format?

What the mixed case encodes

An Ethereum address is 40 hex characters, and hex is case-insensitive, so aBc and abc are the same address. EIP-55 uses that freedom to embed a checksum: each letter's case is determined by the corresponding character of a hash of the lowercase address. The result looks like an ordinary address, but a wallet that validates the pattern will reject an address where a typo breaks the expected casing, which is real protection against sending funds into the void.

When to checksum and validate

Convert an all-lowercase address to its checksummed form before publishing it on a site, in documentation or in a payment request, so recipients' wallets can verify it. And when you receive a mixed-case address, validate it: if the casing does not match the checksum, the address has been mangled somewhere and should not be used. An all-lowercase address is still valid but offers no typo protection.

Nothing leaves your browser

Addresses you are about to send funds to are sensitive context. The checksum conversion and validation run entirely in your browser, with no server involved and nothing logged.

Step by step

1. Paste the address. Open the checksum tool and paste the 0x address.
2. Convert or validate. Get the EIP-55 checksummed form, or check whether a mixed-case address passes validation.
3. Use the checksummed form. Publish and share the mixed-case version so wallets can catch typos.