What a hash does
A cryptographic hash function turns any input into a fixed-length fingerprint. The same input always gives the same hash; change one letter and the hash changes completely; and you cannot work backwards from the hash to the input. That makes hashes good for checking that a file or message has not been altered.
Which algorithm?
- SHA-256 - the standard everyday choice for integrity checks.
- SHA-384 / SHA-512 - longer variants, used in some protocols and signatures.
- SHA-1 - broken for security (collisions can be made). Only use it for non-security checksums or compatibility.
Do not hash passwords with these
Plain SHA hashes are fast, which helps attackers guess passwords. Websites should store passwords with a slow, salted algorithm such as Argon2, scrypt or bcrypt. MD5 is not offered here because it is unsuitable for anything security-related.
Frequently asked questions
Is the text sent to a server?
No. Hashing uses your browser's built-in Web Crypto API.
Why do I get a different hash than a file checksum?
This tool hashes text typed here (UTF-8). A file checksum hashes the file's raw bytes, including line endings.
Can I reverse a hash?
No. Hashes are one-way.