Bcrypt Hash Generator & Checker
Hash and verify passwords with Bcrypt — entirely in your browser.
Your passwords are never sent to any server.
🔒 Generate Bcrypt Hash
✅ Check Bcrypt Match
About
A free tool for backend developers and security engineers to instantly generate Bcrypt password hashes and verify them — all without leaving the browser.
This tool runs 100% locally. Your passwords are processed entirely in the browser via a Web Worker and are never sent to any server.
How to Use
Hash a password
Enter a plain-text password in the left panel, set the cost Rounds (10 is recommended), and click "Generate Hash". Copy the result to use in your app.
Verify against an existing hash
Paste an existing Bcrypt hash ($2b$10$...) and the plain-text password in the right panel, then click "Compare" to see if they match.
Glossary
- bcrypt
- A password-hashing algorithm designed to be slow and costly to compute. It automatically generates a salt and applies key stretching, making it highly resistant to rainbow table and brute-force attacks.
- Hash
- A fixed-length string produced from an input by a one-way function. It is computationally infeasible to reverse a hash back to the original input, so authentication is done by re-hashing and comparing.
- Salt
- A random string appended to a password before hashing. Because each salt is unique, two identical passwords produce different hashes, neutralising rainbow table attacks.
- Cost Factor (Work Factor / Rounds)
- A parameter that controls how many times the bcrypt algorithm iterates (as a power of 2). Each increment doubles computation time, allowing you to keep up with future hardware improvements.
- Rainbow Table Attack
- An attack that uses a precomputed table of hash values to crack passwords. The use of unique salts in bcrypt makes this attack ineffective.
- Brute-Force Attack
- An attack that systematically tries every possible password candidate. Because bcrypt is intentionally slow to compute, it dramatically reduces the practicality of brute-force attempts.
- Key Stretching
- A technique that runs the hash computation many times to intentionally increase the time per verification. In bcrypt, the cost factor controls how many iterations are performed.
FAQ
- Q.Is my password sent to your server?
- No. All bcrypt hashing and comparison is performed entirely in your browser's JavaScript environment. Your passwords and hashes never leave your device.
- Q.Is bcrypt still considered secure?
- Yes. Since its publication in 1999, bcrypt remains one of the most widely recommended password-hashing algorithms. With an appropriate cost factor it provides strong protection against modern hardware attacks.
- Q.What is the recommended cost factor (rounds)?
- As of 2024, a cost factor of 12–14 is generally recommended. Aim for a value where a single hash takes roughly 0.25–1 second on your server so it remains usable while resistant to attacks.
- Q.What is the difference between bcrypt and SHA-256?
- SHA-256 is a fast general-purpose hash — too fast for password storage, giving attackers an advantage. bcrypt is designed specifically for passwords: it is intentionally slow and includes an automatic salt.
- Q.Where would I use the generated hash?
- In web application authentication, you store the bcrypt hash in your database instead of the plain-text password. At login, you re-hash the entered password and compare it to the stored hash.
- Q.Can I reverse a bcrypt hash to get the original password?
- No. bcrypt is a one-way function. It is computationally infeasible to derive the original password from the hash — that is the fundamental property that makes it safe for password storage.
- Q.Can I use this on a smartphone?
- Yes. However, with a high cost factor set, hashing may take noticeably longer on mobile devices due to slower processors compared to desktop hardware.
Use Cases
Password Storage Testing
Verify your backend API's password storage implementation without writing a single line of code.
Login Debugging
Quickly check whether a hash stored in your database actually matches the expected plain-text password to isolate auth bugs.
Security Learning
Experiment with different cost factors to understand how bcrypt's work factor affects computation time and security strength.
Cost Benchmarking
Compare cost factor 10 vs 12 to measure the performance impact before updating your production configuration.