SHA-3 Hash Generator
Generate SHA3-224, SHA3-256, SHA3-384 and SHA3-512 hashes from text — or drop in a file to checksum it, and paste a known hash to see which variant it matches.
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.
Built and maintained by Meet Shah · Last updated
What this tool is used for
- Producing a digest that is structurally unlike SHA-2, as a hedge against a future weakness in that family.
- Matching a protocol or standard that specifies SHA-3 explicitly rather than SHA-2.
- Taking advantage of native length-extension resistance without a truncated variant or HMAC.
- Comparing sponge-based and Merkle-Damgard output for a standards exercise.
- Reproducing a value from a system that chose FIPS 202.
Frequently Asked Questions
- Is SHA-3 a replacement for SHA-2?
- No — it is an alternative with a completely different internal design. NIST standardised it in 2015 after the Keccak team won the public competition, so that a future break of the Merkle-Damgård family would not leave the world without a trusted hash. SHA-2 remains fully recommended.
- What is a sponge construction?
- Input is absorbed into a large internal state (1600 bits) by XOR and permutation, then output is squeezed back out. Because the state is far larger than the digest, the attacker never sees enough of it to continue hashing — SHA-3 is immune to length extension by design.
- What are SHAKE128 and SHAKE256?
- Extendable-output functions from the same Keccak permutation: you request as many output bits as you like. They are used where a variable-length pseudorandom stream is needed, such as in post-quantum schemes like ML-KEM and ML-DSA.
- Is SHA-3 the same as Keccak?
- Almost, but not byte-for-byte. NIST changed the domain-separation padding before standardising, so original Keccak-256 and SHA3-256 produce DIFFERENT digests for the same input. Ethereum uses the original Keccak-256, which is a frequent source of confusion.
- Is it slower than SHA-2?
- In software, usually yes — SHA-2 benefits from years of tuning and from CPU instructions that SHA-3 cannot use. SHA-3 is competitive in hardware and its security margin is generous, so the tradeoff is deliberate.
Common errors and gotchas
- Expecting it to replace SHA-2. It was standardised as an alternative, and SHA-2 remains unbroken and recommended.
- Confusing SHA-3 with Keccak as submitted. The padding changed during standardisation, so outputs differ.
- Assuming it is faster. In software it is often slower than SHA-2, which is part of why adoption has been gradual.
- Reaching for SHAKE when a fixed-length digest is what the protocol wants. They are different primitives.
- Assuming universal library support, which is still thinner than for SHA-2.