Password hash generator
Turn a password into a bcrypt, SHA-256, SHA-512 or SHA-1 hash, and feel the difference between a hash built for speed and one built to resist cracking.
bcrypt
slow, salted: good for storageEach +1 on the cost doubles the time. Try 10, then 12, then 14: that slowdown is exactly what an attacker with a stolen database has to pay per guess.
SHA family
fast, unsalted: never for storing passwords———Verify a password against a bcrypt hash
Fast hashes vs password hashes
SHA-256 is built to be fast: a single high-end GPU computes billions of them per second. That's ideal for checking a download hasn't been tampered with, and exactly wrong for passwords, because an attacker with a leaked table can test guesses at the same speed.
bcrypt (1999), scrypt (2009) and Argon2 (winner of the 2015 Password Hashing Competition) add a random salt and a tunable work factor. The salt means identical passwords get different hashes. The work factor means each guess costs real time and, for scrypt and Argon2, real memory. See how much that matters on the crack time calculator.
The OWASP Password Storage Cheat Sheet gives current parameter recommendations for each algorithm.
Hash generator FAQ
Which hash should I use to store passwords?
Use a slow, salted password hashing function. OWASP’s Password Storage Cheat Sheet recommends Argon2id first, then scrypt, then bcrypt for legacy systems, or PBKDF2 where FIPS compliance is required. Never store passwords with plain MD5, SHA-1 or SHA-256: they are designed to be fast, which helps attackers.
Why does bcrypt give a different hash each time?
bcrypt generates a random 16-byte salt for every hash and stores it inside the result. The same password therefore produces a different hash each time, which stops attackers from using precomputed tables or spotting users who share a password. Verification reads the salt back out of the stored hash.
What is the bcrypt cost factor?
The cost is the base-2 logarithm of the number of key-expansion rounds. Each +1 doubles the time to compute a hash, for you and for an attacker. Pick the highest cost that keeps a login under a comfortable delay on your server; 10 to 12 is common today.
Is it safe to hash a real password here?
Hashing runs in your browser with the Web Crypto API and the bcryptjs library. Nothing is sent to a server. That said, use this tool for testing and learning; production hashes should be generated by your application’s own backend library.
Can a SHA-256 hash be reversed?
Not mathematically, but that doesn’t make it safe for passwords. Attackers simply hash billions of guesses per second and compare. That’s why fast hashes appear at the dangerous end of our crack time calculator.