Hash Generator (SHA)
Text in, hex digest out. Four algorithms at once, plus a comparison field for verifying a checksum.
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Worked example
Hashing hello gives SHA-256 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824. Change one letter and none of the 64 hex characters survive.
A cryptographic hash maps any input to a fixed-length digest. It is one-way, deterministic, and avalanche-sensitive: flipping a single bit of input changes about half the output bits. That is what makes it useful for integrity checks — a downloaded file either matches the published digest or it does not.
Which algorithm
SHA-256 is the default for integrity and signatures. SHA-384 and SHA-512 are stronger and faster on 64-bit hardware but produce longer strings. SHA-1 is included for legacy checksums and old protocols; it is broken for collision resistance, meaning two different inputs can be crafted with the same digest, so do not use it where an attacker chooses the input.
The comparison field
Paste a published digest into the last field and the page tells you whether any of the four algorithms produce it. This is the practical use: verifying that a release archive matches the checksum its author published. If none match, the file is not the file the author signed.
Hashing is not encryption
There is no key and no way back. Hashing a password for storage is not enough on its own either — fast hashes are the wrong tool for that, because an attacker who steals the digest can test billions of candidates per second. Password storage needs a deliberately slow, salted function such as bcrypt, scrypt or Argon2.