Bcrypt is a robust password-hashing function based on the Blowfish cipher. It was developed to specifically address the vulnerabilities of fast hashing algorithms like MD5 and SHA-256 when storing passwords. Its primary defense mechanism is its adjustability and slowness.
By making the hashing process computationally expensive (customizable via "Salt Rounds"), Bcrypt ensures that even if a database is compromised, attackers cannot easily use brute-force methods or rainbow tables to crack the passwords.
Adjustable Security
Control the "Work Factor" (1-31). Higher rounds make the hash exponentially harder to crack but slower to generate.
Built-in Salting
A unique 128-bit salt is automatically generated and embedded into the hash string, defeating rainbow table attacks.
Instant Verification
Easily check if a plain-text password matches a stored Bcrypt hash without needing a backend server.
Why Use This Tool?
100% Client-Side Privacy
Security is our top priority. Your passwords are processed locally in your browser using JavaScript. They are never transmitted to our servers.
Batch Processing
Need to generate test data? Our Batch Mode lets you hash hundreds of passwords at once, perfect for seeding databases.
How to Use
Generating Hashes
1. Enter your password in the input field.
2. Adjust the Salt Rounds (10 is standard, 12 is stronger).
3. Click Generate Hash.
4. Copy the resulting string for storage.
Verifying Passwords
1. Switch to the Check / Verify tab.
2. Enter the plain text password.
3. Paste the Bcrypt hash string you want to check.
4. Click Verify Match to see the result.
Frequently Asked Questions
What is Bcrypt?
Bcrypt is a password-hashing function designed by Niels Provos and David Mazières. It is based on the Blowfish cipher and is specifically designed to be slow and computationally expensive, making it resistant to brute-force attacks and rainbow table lookups.
What are Salt Rounds (Work Factor)?
Salt rounds (or cost factor) determine the computational complexity of the hashing process. It is logarithmic; increasing the rounds by 1 doubles the time it takes to generate a hash. A value of 10-12 is currently standard for good security without sacrificing too much performance.
Why does the hash change every time?
Bcrypt automatically generates a random "salt" for every hash operation. This salt is included in the final output string. Because the salt is random and different each time, the resulting hash will also be different, even for the exact same password.
Can I decrypt a Bcrypt hash?
No, Bcrypt is a one-way hashing function, not an encryption method. You cannot decrypt it to get the original password back. You can only verify if a candidate password matches the hash by re-hashing the password with the same salt.
Is it safe to use this tool online?
Yes. This tool runs entirely in your browser using client-side JavaScript (bcryptjs). Your passwords are never sent to any server, ensuring complete privacy and security.
What is the format of a Bcrypt hash?
A standard Bcrypt hash string looks like this: $2a$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy. It consists of the algorithm identifier ($2a$ or $2b$), the cost factor (10), the 22-character salt, and the 31-character full hash.
How do I verify a password match?
Use the "Check / Verify" tab in this tool. Paste the plain text password and the Bcrypt hash string. The tool will use the salt from the hash to re-compute the value and tell you if they match.
Why is Bcrypt better than MD5 or SHA-256?
MD5 and SHA-256 are designed to be fast, which makes them vulnerable to modern hardware that can guess billions of passwords per second. Bcrypt is designed to be slow ("key stretching"), making brute-force attacks impractical.
What is the maximum password length for Bcrypt?
The standard Bcrypt implementation has a limit of 72 bytes for the input password. Any character beyond the 72nd byte is ignored. If you validly need longer passwords, consider pre-hashing them with SHA-256 before passing to Bcrypt.
Can I generate hashes in bulk?
Yes, enable "Batch Mode" in the generator tab. You can paste a list of passwords (one per line) and generate hashes for all of them simultaneously.