Hash generator
The digest appears here as you type
Hashed in your browser · the file is never uploaded
A hash turns any input into a fixed-length fingerprint. The same input always gives the same output, a one-character change gives a completely different one, and there is no way back to the original. That makes it useful for checking that something has not changed, and useless as a way of hiding it.
How to generate a hash
Which one to use depends entirely on why. For anything security-related, SHA-256 or SHA-512. For verifying a download against a checksum published years ago, whichever the publisher used, which is often MD5 or SHA-1. Both are broken against a deliberate attacker but still perfectly good at catching a corrupted transfer. CRC-32 is not a cryptographic hash at all; it is an error-detecting code, which is why ZIP files carry one. One thing that trips people up: this hashes the bytes of the text as UTF-8, so an accented character or an emoji contributes more than one byte and the digest reflects that.
Questions
No. Hashing throws information away by design. What attackers do instead is hash enormous lists of likely inputs and look for a match, which is why hashing a password without a salt is not enough.
SHA-256 unless something specific requires otherwise. It is fast, well-studied and has no known practical weaknesses.
Not against an attacker. Two different files with the same MD5 can be constructed in seconds. It is still fine for spotting accidental corruption.
No. Password storage needs a slow, salted function such as bcrypt, scrypt or Argon2. A fast hash is exactly the wrong tool.
No. SHA hashing uses the browser’s built-in WebCrypto and MD5 runs in code that shipped with this page. There is no request.
Almost always a trailing newline or a different text encoding. Check for a stray line break at the end of what you pasted.