Generate SHA-3 / Keccak digests
Compute SHA-3 (Keccak) hashes in any of the four standard sizes. Used by Ethereum (keccak256), TLS 1.3 and modern protocols. Runs entirely in your browser.
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How to compute SHA-3
Hashes UTF-8 bytes with the Keccak permutation via @noble/hashes. Output is lowercase hex.
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Type or paste text
Any UTF-8 input — emoji and accents are hashed faithfully.
Bytes flow through
TextEncoder/TextDecoderfor predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.inputUTF-8TextEncoderlosslessliveinput · raw bytestext · UTF-8hello
loaded · UTF-8MIME · ready - 02
Pick the output size
224, 256, 384, or 512 bits — depends on the protocol you're matching.
Hash and signature operations call
crypto.subtlefrom the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.sizeWeb Cryptosubtledeterministiclivesize · options256 · live64 hex chars
options applied · livelive - 03
Live hash
Output updates as you type. Uses the sponge construction, not Merkle-Damgård.
Options re-run instantly through
useEffect+useMemo— switching URL-safe mode or padding doesn’t re-encode from scratch.livememoisedoptionsinstantreactiveout · encodedready · ready69070dda…
encoded · livelossless - 04
Copy or download
One click to clipboard. Download as .txt.
Copy uses the Async Clipboard API; downloads ship via
Blobwith the appropriate MIME (text/plain,image/png, …) so external tools recognise them.exportclipboardblobMIME-correctclient-sideok · copiedready · doneCopied
shipped · ready to shipsuccess
Encoding without surprises
Always UTF-8 first
Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.
URL-safe vs standard Base64
Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.
Hashes aren’t passwords
SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.
Watch padding rules
Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.
Use Web Crypto for keys
Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.
JWT decode ≠ verify
Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.
When to use SHA-3
Modern protocols that want a non-Merkle-Damgård hash.
Ethereum keccak256
Compute address and contract-call hashes. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.
web3TLS 1.3
Pair SHA3 with HKDF in modern protocols. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.
OpenSSL-matchedDigital signatures
Sign a SHA3 digest with EdDSA or ECDSA. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.
losslessPost-quantum readiness
Some PQ schemes specify SHA-3 internally. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.
byte-identicalSponge primitives
Build MACs, KDFs, or PRFs on top of Keccak. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.
spec-gradeTest fixtures
Match NIST test vectors exactly. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.
production-readyFrequently asked questions
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