Keccak-256 is the 256-bit output of the original Keccak sponge, the function that won NIST's SHA-3 competition in 2012. Ethereum adopted it before SHA-3 was finalised with different padding, so Keccak-256 and SHA3-256 give different digests, and Ethereum's is this one.

Where does Ethereum use Keccak-256?

Nearly everything. An address is the last 20 bytes of the Keccak-256 of the public key; transaction and block hashes are Keccak-256; Solidity's keccak256 (and its misnamed sha3) and the function selectors in every contract call (the first four bytes of the Keccak-256 of the signature) are too. EIP-55 checksummed addresses are cased by it as well.

How does Keccak work?

Keccak is a sponge: a 1600-bit state absorbs the input in blocks, applying a 24-round permutation after each, then the digest is read from the first bits of the state. The capacity, the part of the state never output, is twice the digest size, and that is the security margin. No length-extension attack exists against it.

Is Keccak-256 secure?

Yes: it is the same permutation as SHA3-256 with the same 512-bit capacity, so the same 128-bit security, and no attack on the full function is known. Ethereum's whole value depends on it, and it has held.

How does SHA-3 differ from Keccak?

Only in the padding. NIST appended two bits to the message before the Keccak padding when it standardised SHA-3 in 2015, so SHA-3 digests differ from the original Keccak's for every input. Ethereum adopted Keccak-256 before the change and kept it, so what Solidity calls sha3 or keccak256 does not match SHA3-256. This tool gives you both families; pick the one the other side uses.

Is my file uploaded anywhere?

Nothing leaves your browser. The file is read on your machine and hashed there, by the browser's Web Crypto API or a WebAssembly build of Keccak-256 loaded on first use; the page makes no request with its bytes. You can load the page, go offline and keep hashing.

How do I hash a file?

Drop the file onto the pane or choose it with the button. It is read into memory and hashed at once, with no size steps and no upload progress because there is no upload. Files up to 1 GB work; a 100 MB file takes well under a second on Keccak-256.

How do I verify a download's Keccak-256 digest?

Paste the digest the publisher gave you into the Verify field, in hex of either case, with or without spaces, colons or a 0x prefix, or in Base64. The tool says whether it matches the file you dropped. A match means the bytes are exactly the ones that were published.

What formats can I copy or download?

Hex by default, 64 characters; Base64 and Base64url are one click away and re-encode the same 32 bytes. The download button saves a line in the `digest filename` form that sha256sum-style tools read.

Can I key the file hash (HMAC)?

Yes: turn on HMAC and enter the secret, and the file is signed with HMAC-Keccak-256 rather than hashed, the same construction a server uses to sign an upload or a webhook payload.

File to Keccak-256.

Drop a file and read its Keccak-256 digest at once, in your browser. Keccak-256 is the original Keccak at 256 bits, the hash behind every Ethereum address, transaction and contract call; the file is read on your machine and never uploaded.256 bits1 GB max file2012 published0 bytes uploaded

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How it works

4 steps, no account. It runs in your browser and nothing is uploaded.

Drop a file
Drop it onto the pane or choose it with the button; anything up to 1 GB is read in your browser.
Read the digest
The Keccak-256 digest appears at once, as hex, Base64 or Base64url; switch to Keccak-224, Keccak-384 and Keccak-512 in the bar.
Verify against a published checksum
Paste the digest the publisher lists and the tool says whether the file matches.
Copy or download
Copy the digest, or download it as a line a checksum tool can read.

Nearby in the hash generators. Every one free, in the browser.

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For personal projects & open source

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Client work, SaaS products and anything you charge for.Commercial use: Personal & open source only
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Complete multi-page sites you can ship as they are.Templates: All 14 templates
React icons from every major library, installable with one command.React icons: 294k+ icons
Presets that restyle every block, in light and dark.Themes: All 59 themes
Lets your AI editor search, preview and install blocks for you.MCP server: Basic usage
Priority requests are answered first.Support: Standard

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File to Keccak-256.