SHA-3 Hash Generator

How SHA-3 hashing works

SHA-3 is the NIST-standardized hash family defined in FIPS 202, built on the Keccak sponge construction that won the 2007-2012 NIST hash function competition. Unlike SHA-1 and SHA-2, which are Merkle-Damgård constructions, SHA-3 absorbs input into a 1600-bit internal state through a 24-round permutation and then squeezes out a digest of the requested length — 224, 256, 384, or 512 bits. This structural difference means a SHA-3 collision or preimage attack would need an entirely different approach than one targeting SHA-2, which is why many protocols use both families side by side for defense in depth.

A subtle but important detail: SHA-3's final padding uses the 0x06 domain-separation suffix specified in FIPS 202. The original 2008 Keccak submission (before NIST finalized the standard) used a different 0x01 pad byte — that variant is what Ethereum calls keccak256, and it produces completely different digests from real SHA-3 for the same input. This tool implements the finalized FIPS 202 padding, so its output matches the official NIST SHA-3 test vectors exactly.

Everything above runs synchronously in your browser using a small pure-JavaScript Keccak permutation — no library upload, no server round-trip, and no data ever leaves your device.