Verify an HMAC authentication code without exposing the secret key to the server.
A hash turns any input into a short, fixed-length fingerprint. The same input always gives the same digest, and changing a single byte gives a different one. That makes hashes the standard way to check a download, compare two files or store a password without keeping the password itself.
This category covers the SHA-2 and SHA-3 families, BLAKE2 and BLAKE3, Keccak and SHAKE, and the legacy MD4, MD5 and SHA-1 for older systems that still expect them. For error detection there are CRC-32, CRC-64, Adler-32 and FNV checksums. Keyed and password hashing come with matching verifiers: HMAC, and Argon2id. ROT13 and ROT47 sit here too, as simple letter rotation ciphers.
Tools marked Runs in your browser hash your text and files on your own device.
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