SHA-3 (Keccak) Hash Generator (Free)
Free tool: calculate the SHA-3 (Keccak) hash of any string instantly in your browser. Standardized by NIST in 2012, SHA-3 uses a fundamentally different "sponge construction" from SHA-2, serving as an independent safety net.
What Is SHA-3 Hashing?
SHA-3 hashing converts the string you enter into a fixed 256-bit (32-byte) value. SHA-3 is the newest generation of hash function, standardised by NIST in 2012: the same input always yields the same hash, while working the original string back from the hash is computationally impossible — the «one-way» property. This tool computes the SHA-3 hash in your browser in real time as you type into the input box.
SHA-3's defining feature is that it uses a fundamentally different design from SHA-2 (SHA-256, SHA-512 and so on), called a «sponge construction». Should some vulnerability ever be found in SHA-2, SHA-3 is thought unlikely to be affected because the design principle differs — which is why it is positioned as cryptographic «insurance». The calculation happens entirely inside your browser; the string you enter is never sent to a server.
How to Use the SHA-3 Hash Calculator
- Enter the string you want hashed Type into the input box whatever you want a hash for — a password, the contents of a file, and so on.
- Read the SHA-3 hash As you type, the 256-bit SHA-3 hash appears in real time as a hexadecimal string.
- Copy it if you need to Press «Copy» and the hash currently shown goes to your clipboard, ready to paste straight into test code or a comparison.
Tips for getting more out of it
- SHA-3 is based on the Keccak algorithm selected through a NIST competition (2007–2012). Like SHA-2, it supports multiple output lengths; this tool uses the 256-bit output.
- While SHA-2 uses a Merkle–Damgård construction, SHA-3 adopts a "sponge construction" — a fundamentally different design philosophy. This means attacks that work against SHA-2 cannot be directly applied to SHA-3.
- No known vulnerabilities have been found in SHA-3. However, SHA-256 has a far larger track record in production, so for systems prioritizing compatibility with existing infrastructure, SHA-256 remains the practical choice.
- Ethereum uses its own Keccak-256 — the version of Keccak before NIST finalized the SHA-3 standard — which differs subtly from NIST SHA-3. Ethereum-specific hash computations require dedicated implementations.
- SHA-3's bit-manipulation-based design lends itself to efficient hardware implementations (FPGA/ASIC). In software, it can be slightly slower than SHA-256.
When SHA-3 Hashing Comes in Handy
Verifying a hash function in a new system
When you are weighing SHA-3 for a system you are about to design, you can check the actual output in the browser at once and line it up against what your implementation produces.
Understanding specifications that use Keccak-family hashes
While researching a specification that adopts its own Keccak-256 — as Ethereum does — it helps to compare the output against NIST-standard SHA-3-256 hands-on.
As teaching material for cryptography and algorithm comparison
If you want to see how far SHA-3 and the SHA-2 family diverge for the same input, lining them up in the multi-hash calculator makes the point clearer.
Deciding between SHA-3 and SHA-256
When you are unsure whether compatibility with an existing system should push you to SHA-256, you can generate both hashes and check the format you will write into the specification. For SHA-256 use the SHA-256 hash calculator.
SHA-3 Terms Explained
- SHA-3
- The name of the hash function NIST standardised in 2012, which internally uses the Keccak algorithm. Four output lengths are defined — 224, 256, 384 and 512 bits — and this tool uses the 256-bit output.
- Keccak
- The algorithm designed by a Belgian research group and chosen in NIST's SHA-3 competition. «SHA-3» is what it is called after NIST's standardisation; Keccak itself refers to a broader concept that predates it.
- Sponge Construction
- SHA-3's design approach, in which input data is «absorbed» into an internal state and output is «squeezed» out to whatever length is needed. It differs from the Merkle–Damgård construction that SHA-2 adopts — a structural difference that makes attacks on SHA-2 hard to carry over.
- Collision Resistance
- The property that makes it hard for two different inputs to produce the same hash. No practical collision-finding attack has been found against SHA-3 to date, so it can be used safely for digital signatures and tamper detection.
- How It Differs from SHA-2
- SHA-2 (SHA-256, SHA-512 and so on) and SHA-3 have similar names but are entirely separate lines of algorithm with quite different internals. NIST did not seek a replacement for SHA-2 but an alternative should SHA-2 ever be broken.
- One-Way Hash Function
- A function for which computing the output from an input is easy, but working the input back from the output is computationally impossible. SHA-3 has this property too, so it can be used safely for tasks such as verifying passwords.
FAQ
Side Note — The Birth of Keccak and the NIST Competition: Five Years to Crown the Next Standard
In 2006, as collision attacks on SHA-1 began to look increasingly realistic, NIST launched the "SHA-3 Competition." Sixty-four algorithms were submitted from around the world. After approximately five years of evaluation, in October 2012 Keccak — designed by a Belgian team (Joan Daemen, Gilles Van Assche, Guido Bertoni, Michaël Peeters) — was selected. Daemen had previously co-designed AES (Rijndael), making this a remarkable "double crown" in modern cryptography.
What makes the SHA-3 competition fascinating is that NIST was not seeking a replacement for SHA-2, but rather insurance against SHA-2 being broken. SHA-2 has remained secure to this day, so SHA-3 is positioned as a parallel standard. The fundamental difference in design means attacks against SHA-2 cannot be directly applied to SHA-3.
Keccak's "sponge construction" models data processing as absorbing input and then squeezing out however many output bits are needed. This design has also been extended into SHAKE128 and SHAKE256 — extendable-output functions (XOFs) that can produce arbitrary-length output — opening new possibilities in cryptographic design.