Generate and verify bcrypt password hashes instantly. Adjustable cost factor (4–31 rounds) with automatic salt generation. No data is stored or transmitted — everything runs in your browser.
Bcrypt is a password hashing function designed by Niels Provos and David Mazières in 1999, based on the Blowfish cipher. Unlike general-purpose hash functions like MD5 or SHA-256, bcrypt is specifically engineered for securely storing passwords. It incorporates three critical security features that make it the industry standard:
Automatic salting. Every bcrypt hash includes a unique, randomly generated 128-bit salt embedded directly in the output. This means even if two users have the same password, their hashes will be completely different — making rainbow table attacks useless.
Adaptive cost factor. The "rounds" parameter (also called cost factor) controls how many iterations of the hashing algorithm are performed. Each increment doubles the computation time. As hardware gets faster over the years, you simply increase the cost factor to maintain the same level of security.
Intentional slowness. While SHA-256 can compute billions of hashes per second, bcrypt at cost 10 takes about 100ms per hash. This is negligible for a legitimate user logging in, but catastrophic for an attacker trying millions of guesses.
A bcrypt hash always follows this structure: $2b$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy
$2b$ — The algorithm identifier (bcrypt version 2b). You may also see $2a$ or $2y$ in older hashes — they are functionally equivalent in most implementations.
10$ — The cost factor (10 rounds, meaning 210 = 1,024 iterations of the key derivation).
First 22 characters after the cost — The Base64-encoded 128-bit salt.
Remaining 31 characters — The Base64-encoded 184-bit hash of the password + salt.
The right cost factor depends on your application's requirements. Cost 10 (~100ms) is the most common default and suitable for most web applications. Cost 12 (~300ms) is recommended for higher-security systems like banking or healthcare. Cost 14+ is used for extremely sensitive applications but may cause noticeable login delays.
The key principle: choose the highest cost factor that doesn't create an unacceptable delay for your users. On a modern server, cost 10–12 is the sweet spot for most applications.
MD5 / SHA-256 — These are general-purpose hash functions designed for speed. They compute billions of hashes per second, which makes them terrible for password storage. An attacker with a GPU can try billions of password guesses per second against an MD5 or SHA-256 hash.
Bcrypt — Purpose-built for passwords with adaptive cost, built-in salting, and intentional slowness. Industry standard for over 20 years.
Argon2 — The winner of the 2015 Password Hashing Competition. It adds memory-hardness (requires large amounts of RAM), making it resistant to GPU and ASIC attacks. Argon2 is technically superior, but bcrypt remains more widely supported across frameworks and languages.
Yes. This tool runs 100% in your browser using the bcrypt.js library. No passwords or hashes are transmitted to any server, stored in any database, or logged anywhere. The salt is generated using your browser's cryptographically secure random number generator. You can verify this by disconnecting from the internet — the tool will continue to work perfectly.