What this does
Computes MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes of text you type or a file you choose. A hash is a fixed-length fingerprint of the input: the same input always produces the same hash, and changing even one byte produces a completely different one.
Choosing an algorithm
SHA-256 is a solid general-purpose default. MD5 and SHA-1 are fast and still useful for things like checking a file download matches the original, but both have known weaknesses and should not be used for passwords, signatures, or anything security-sensitive.
Privacy
This runs entirely in your browser. Nothing is uploaded.