Hash Generator

Hashes in 30 seconds

A hash function takes any input — a word, a file, a billion bytes — and produces a fixed-size fingerprint. Same input always gives the same fingerprint. The hash is one-way: you can't recover the input from the hash.

What hashes are used for

• File integrity — "this download wasn't tampered with"
• Password storage — never store passwords; store their hash (with salt)
• Deduplication — same hash = same data
• Digital signatures — sign the hash, not the whole document
• Blockchains — every block contains the previous block's hash

Which algorithm should I use?

• SHA-256 — the modern default. Use this unless you have a specific reason not to.
• SHA-512 — twice the output size, faster on 64-bit systems, used in some legacy systems.
• SHA-1 — deprecated. Collisions have been found in practice. Don't use for new systems.
• MD5 — broken since 2004. Collision attacks are trivial. Still appears in legacy file checksums (e.g., old Linux mirror lists).

For passwords, hashing isn't enough

Real password storage uses purpose-built algorithms — bcrypt, scrypt, argon2 — that are deliberately slow and accept a per-user salt. Hashing a password with SHA-256 is much, much weaker than hashing with bcrypt.