Which algorithm should I use?

SHA-256 for anything current. MD5 and SHA-1 are both cryptographically broken — collisions can be produced deliberately — and should only be used to check for accidental corruption, never for security. SHA-512 is fine and marginally faster than SHA-256 on 64-bit hardware.

Can a hash be reversed?

Not mathematically, but a common input can be looked up. Every dictionary word and every leaked password has a precomputed hash in a public rainbow table, so hashing alone does not protect a password — that needs a slow, salted algorithm like bcrypt or Argon2.

Should I use this to hash passwords for my app?

No. SHA-256 is designed to be fast, which is exactly wrong for passwords — a GPU tests billions per second. Use bcrypt, scrypt or Argon2, which are deliberately slow and salted. This tool is for checksums and fingerprints.

Hash Generator

Generate MD5, SHA-1, SHA-256 or SHA-512 hashes from any text, using the browser's built-in Web Crypto API. Useful for verifying a checksum or comparing two files' fingerprints. The input never leaves your browser — which matters, because whatever you are hashing is often a secret.

Runs in your browser — nothing is uploaded

Questions

Which algorithm should I use?: SHA-256 for anything current. MD5 and SHA-1 are both cryptographically broken — collisions can be produced deliberately — and should only be used to check for accidental corruption, never for security. SHA-512 is fine and marginally faster than SHA-256 on 64-bit hardware.
Can a hash be reversed?: Not mathematically, but a common input can be looked up. Every dictionary word and every leaked password has a precomputed hash in a public rainbow table, so hashing alone does not protect a password — that needs a slow, salted algorithm like bcrypt or Argon2.
Should I use this to hash passwords for my app?: No. SHA-256 is designed to be fast, which is exactly wrong for passwords — a GPU tests billions per second. Use bcrypt, scrypt or Argon2, which are deliberately slow and salted. This tool is for checksums and fingerprints.