Hash Generator

MD5, SHA-1, SHA-256 and SHA-512 hashes for any text, with optional HMAC key.

A hash is one-way and fixed-length: any input, from an empty string to a gigabyte, comes out the same size, and there is no route back. The property that makes it useful is that changing a single bit of input changes roughly half the output bits, so a hash is a cheap way to answer "are these two things identical" without comparing them.

MD5 and SHA-1 are here because you still meet them — in old checksums, in legacy integrations, in file manifests — but both are broken for anything security-related, since attackers can construct two different inputs with the same digest. Use SHA-256 or SHA-512 when the answer matters, and note that HMAC is a different job: it proves a message came from someone holding the key, which a plain hash cannot.