Keccak Hash Generator

What is Keccak?

Keccak is the algorithm that won the competition NIST ran to select SHA-3. This tool implements the original submission, at 224, 256, 384, or 512 bits, rather than the standardized version.

Pick a size and feed it typed text or uploaded files. Results include raw digest bytes and lowercase hexadecimal.

Why the original and the standard both exist

During standardization NIST added domain-separation padding to the Keccak design. That change is small, entirely deliberate, and completely alters the output: Keccak-256 and SHA3-256 return different digests for the same input.

By then, systems had already deployed the original. Ethereum is the widely known case, where the hash generally labelled keccak256 is this one and not FIPS 202 SHA-3. Anything built against those systems needs the original, which is why a separate tool exists at all.

Are there alternatives?

SHA3 is the standardized family and the correct choice for anything new or anything specifying FIPS 202. Reach for Keccak only when a protocol or an existing dataset requires the pre-standard version.

For general hashing with no compatibility constraint, SHA256, BLAKE3, and BLAKE2b are all better supported.

Fun facts and more info

Keccak resists length extension, as SHA-3 does. It runs one way, it is not encryption, and it is not built for password storage.

The naming is a genuine source of bugs. Documentation frequently says SHA-3 while meaning original Keccak, or the reverse, and because both produce a plausible looking 32-byte value the mistake surfaces only when two systems compare digests and disagree. If a hash refuses to match and everything else looks right, check this first.