Checksum and Hash Calculator
A hash is only useful if it is the standard one. A digest that is self-consistent but does not match what everybody else computes is worse than none at all, because it will disagree with the file you are checking against. Getting the same answer twice proves nothing; getting the answer the rest of the world gets proves the point, so that is what is checked here.
What this generator does
Turns your text into UTF-8 bytes and works out the digest, then reports how much of that digest changes if a single input bit does.
How to use this tool
- Paste the text you want a digest of.
- Choose the algorithm.
- Copy the digest.
- Note how much of it changes when you alter a single character.
Understanding the controls
- Your text
- Up to two hundred thousand characters. The digest is taken over the bytes, so accents and emoji count for more than one character each.
- Algorithm
- SHA-256 for anything that needs to be trustworthy, CRC-32 and Adler-32 for detecting damage, FNV-1a for a fast non-secure hash.
Common use cases
- Checking a SHA-256 digest quoted alongside a download
- Working out the CRC-32 of a string for a protocol or a format
- Comparing two pieces of text by their digests
- Seeing how a cryptographic hash scatters a small change
- Producing a stable identifier from a piece of text
How this generator works
Each algorithm is run against its published test vectors — the CRC-32 check value of 0xCBF43926, the SHA-256 worked examples from the specification, the Adler-32 example from the zlib documentation — and must match to the last character. A one-bit change is also made to the input and the digests compared, which shows how a cryptographic hash scatters a small change and an error-detecting checksum does not.
Randomness and fairness
Nothing is random. The same text always gives the same digest, on any device.
For how randomness is produced across the whole site, see how Generate Random works.
Limitations and good to know
- Text only. Hashing a file needs the file itself, which this does not take.
- SHA-256 is the only cryptographic hash offered; MD5 and SHA-1 are broken for anything security-related and are left out.
- CRC-32, Adler-32 and FNV-1a detect accidental damage and are trivially forged, so none of them is a security check.
- The digest is of the exact bytes given, so an extra newline changes it completely — which is usually the reason two digests disagree.
Privacy and your data
Digests are computed in your browser. Nothing you paste is transmitted or stored.
Related generators
- Text Encoder and DecoderEncodes text as Base64, percent-encoding, HTML entities, hex or binary, and back again — accents and emoji included.
- Damm Check Digit GeneratorAdds a check digit that catches every single mistyped digit and every swap of two neighbours, and proves it by trying them all.
- Hash Avalanche DemonstratorFlips one bit of your text at a time and measures how many of the 32 hash bits change — the avalanche property, measured rather than asserted.
- EAN-13 Barcode GeneratorDraws a real EAN-13 barcode from a number, then reads the bars back the way a scanner would to prove it works.