BYTETOOLS

SHA-3 Hash Generator

Generate SHA3-224, SHA3-256, SHA3-384, SHA3-512 or Ethereum's Keccak-256 hash of text or a file, in hex and Base64, entirely in your browser.

…or drop a file to hash it insteadAny file type, up to 4.0 MB — read locally, never uploaded
256 bits
Digest
1088 bits
Rate
512 bits
Capacity
—
Input bytes

SHA3-256: FIPS 202 padding (0x06). The sponge absorbs 136 bytes per block over Keccak-f[1600].

Digest

Type some text or drop a file and the SHA3-256 digest appears here.

Self-test passed: SHA3-256 and Keccak-256 of the empty string match the published FIPS 202 and Keccak digests.

What is the SHA-3 Hash Generator?

The ByteTools SHA-3 Hash Generator implements Keccak-f[1600] directly: the theta, rho, pi, chi and iota steps across 24 rounds with the standard round constants and rotation offsets, wrapped in a sponge that absorbs at the rate for whichever digest length you pick.

  • All four FIPS 202 digest sizes plus original-padding Keccak-256 and Keccak-512
  • Hand-written Keccak-f[1600] permutation with BigInt lanes
  • Self-tested on load against the published SHA-3 and Keccak digests
  • Shows sponge rate and capacity so the parameters are never a mystery
  • Hex, 0x-prefixed hex and Base64 output, plus file hashing up to 4 MB
  • Fully offline — nothing is uploaded or stored

How to use the SHA-3 Hash Generator

  1. 1

    Type or paste text into the text box, or drop a file onto the drop zone.

  2. 2

    Pick a variant: SHA3-224, SHA3-256, SHA3-384, SHA3-512, or Keccak-256/512 for Ethereum-style hashing.

  3. 3

    Check the digest, rate and capacity figures to confirm you are on the variant you meant.

  4. 4

    Copy the result as plain hex, 0x-prefixed hex or Base64.

About the SHA-3 Hash Generator

The ByteTools SHA-3 Hash Generator implements Keccak-f[1600] directly: the theta, rho, pi, chi and iota steps across 24 rounds with the standard round constants and rotation offsets, wrapped in a sponge that absorbs at the rate for whichever digest length you pick. All four FIPS 202 sizes are available, plus the original Keccak padding.

That last option matters more than it sounds. Ethereum standardised on Keccak-256 before SHA-3 was finalised, so its hashes use the original 0x01 padding rather than the 0x06 that FIPS 202 specifies. The two produce completely different digests for the same input, and picking the wrong one is a classic source of mismatched addresses and failing signature checks.

Everything runs 100% locally in your browser — no upload, no logging, and the page works offline. The digest length, sponge rate and capacity are shown for each variant, and the implementation verifies itself against the published empty-string digests when the page loads.

Frequently asked questions

What is the difference between SHA-3 and Keccak?

Keccak won the SHA-3 competition, but NIST changed the padding before standardising it — SHA-3 appends 0x06 where original Keccak appends 0x01. The permutation is identical, yet the two give completely different digests, so you must pick the one your system expects.

Which hash does Ethereum use?

Ethereum uses Keccak-256 with the original padding, not FIPS 202 SHA3-256. If you are computing an address, a function selector or a topic hash, choose Keccak-256 on this page — SHA3-256 will give you the wrong answer.

Is SHA-3 better than SHA-256?

It is different rather than strictly better. SHA-256 is still considered secure and is faster in software on most hardware; SHA-3 uses a sponge construction that is immune to the length-extension attacks SHA-256 is vulnerable to, which makes it a cleaner primitive for some protocols.

Why is there a file size limit?

Keccak is implemented here in JavaScript with 64-bit BigInt lanes, which runs at roughly 2 MB per second. The 4 MB cap keeps the page from freezing. For checksumming large downloads, the SHA-256 tools use your browser's native Web Crypto and handle much bigger files.

Is my input sent anywhere?

No. The whole sponge runs in your browser, so your text and files never leave your device and the tool works with no network connection at all.

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