Check a File’s Integrity (Checksum)

Check that a downloaded file is intact: drop it, paste the hash published by the vendor, and the tool confirms the match. Locally.

Drop the file to check

or click to choose it — read locally, nothing is uploaded

Drop a file and paste its reference hash.

100% local processing, nothing is uploaded

How does it work?

A publisher releases the hash (often SHA-256) of their file. Drop the downloaded file and paste that reference hash: the tool recomputes the file’s hash in your browser and tells you whether it matches, character for character.

The algorithm is deduced automatically from the length of the pasted hash (32 characters → MD5, 64 → SHA-256…), and can be changed. The comparison is done in constant time, ignoring case and spaces.

Examples

A Linux ISO image

The website publishes SHA256: 3b8c…. Drop the 4.7 GB ISO: read in chunks, without filling up memory, it gives a hash to compare. Identical = authentic and complete image.

One byte of difference

If a single byte of the file has changed (interrupted download, tampering), the SHA-256 hash is completely different: the verdict switches from “intact” to “modified or corrupted”.

Frequently asked questions

What exactly does “intact” mean?
That the file you have is identical, bit for bit, to the one the reference hash was computed from. This detects accidental corruption and, with a robust algorithm (SHA-256), deliberate tampering.
How is the algorithm guessed?
From the length of the reference hash: 32 hexadecimal characters correspond to MD5, 40 to SHA-1, 64 to SHA-256, 128 to SHA-512. If in doubt, choose it yourself from the list.
Is my data sent anywhere?
No. All the computation happens in your browser, in JavaScript and WebAssembly. Your text, your files and your hashes never leave your device: no network request is made during hashing, and nothing is stored on a server.

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