At a glance
| Input | Text, typed or pasted |
|---|---|
| Algorithms | MD5, SHA-1, SHA-256 — all three at once |
| Output | Lowercase hexadecimal |
| Where it runs | Entirely in your browser — no file is uploaded to a server |
| Price | Free, with no account and no sign-up |
| Offline | Works with no connection after the first visit |
Which algorithm, and for what
SHA-256 is the default answer. It is what package managers, certificates and blockchains use, and there is no practical attack against it.
MD5 and SHA-1 are broken for security. Two different files can be made to share an MD5 hash on a laptop in seconds, and SHA-1 collisions have been demonstrated since 2017. They are still perfectly good for spotting accidental corruption or de-duplicating files, and that is why they are here — not because they are safe against someone trying.
Hashing is not encrypting
A hash is one-way by design: there is no key and nothing to reverse. Sites that claim to "decrypt MD5" are looking the value up in a table of pre-computed hashes of common strings. That works for password123 and not for anything with real entropy.
Which is also why a bare hash is the wrong way to store passwords. Anything fast — MD5, SHA-256, all of them — lets an attacker try billions of guesses a second against a stolen database. Password storage wants bcrypt, scrypt or Argon2, which are deliberately slow and salted.
Verifying a download
Hash the file you received and compare it with the checksum the publisher lists. They should match exactly; a single differing character means the file is not the one they published.
Worth being clear about what that proves. It catches a truncated or corrupted download reliably. It only catches tampering if the checksum came from somewhere the attacker did not also control — a checksum on the same compromised page proves nothing.
Frequently asked questions
Is MD5 still safe?
Not against anyone trying. Collisions can be manufactured in seconds. It is fine for detecting accidental corruption and for de-duplication, and unfit for signatures, passwords or anything security-related.
Can a hash be reversed?
No. Sites offering to "decrypt" one are looking it up in a table of common strings. That finds "password123" and nothing with real entropy behind it.
Which should I use to store passwords?
None of these. Use bcrypt, scrypt or Argon2 — they are slow and salted on purpose. A fast hash lets an attacker test billions of guesses a second against a stolen database.
Is my file uploaded to hash it?
No. It is read and hashed by your browser, which is the only sensible arrangement when the file is the thing you were checking.
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