Keccak-256 Hash

Compute the Keccak-256 digest of text, using the original Keccak padding rather than the NIST-finalised SHA3-256, which is the version Ethereum uses for addresses, transaction hashes and function selectors.

freeworks offlinenothing uploaded
Input
Output
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About keccak-256 hash

Keccak-256 Hash is a small tool that does one job while you watch. Nothing is saved, so a reload gives you a clean start.

There is no account and no upload step. Whatever you paste lives in a variable until you close the tab, and then it does not.

You will find it under Hashes, alongside 15 other tools for the same sort of job.

Runs in this tab, so nothing you type is uploaded.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Hash of an empty string
The well-known keccak256 constant for empty input
Input
Output
Hash hex: c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
Hash of "abc"
The standard Keccak test vector
Input
abc
Output
Hash hex: 4e03657aea45a94fc7d47ba826c8d667c0d1e6e33a64a036ec44f58fa12d6c45
Questions
Does Keccak-256 Hash work offline?+
Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.
Does it remember anything between visits?+
No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.
Is it accurate?+
Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.
Does it make a sound?+
Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.
Can I use Keccak-256 Hash on a phone?+
Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.