Free online bcrypt hash generator and verifier. Generate bcrypt password hashes with adjustable cost factor and verify passwords against existing hashes — all in your browser.
Bcrypt Generator is a free online tool that generates bcrypt password hashes and verifies passwords against existing bcrypt hashes. Bcrypt is the industry-standard password hashing algorithm recommended by OWASP for secure password storage. It includes built-in salting and an adjustable cost factor that makes brute-force attacks computationally expensive. All hashing runs entirely in your browser using the bcryptjs library — your passwords are never sent to any server.
Use Bcrypt Generator when you need to hash a password for storage in a database, verify a password against an existing hash during debugging, or test your application's authentication system. The hash info display shows the algorithm version, cost factor, and salt extracted from any bcrypt hash, helping you understand and debug authentication issues.
The cost factor (also called "rounds" or "work factor") controls how computationally expensive the hash is to generate. Each increment doubles the time: cost 10 takes ~100ms, cost 12 takes ~400ms, cost 14 takes ~1.5s. OWASP recommends a minimum cost factor of 10, with 12 being a good balance between security and performance for most applications. Higher values provide stronger protection against brute-force attacks but increase login time.
Essential terms and definitions related to Bcrypt Generator & Verifier.
An adaptive password hashing function based on the Blowfish cipher, designed to be computationally expensive to resist brute-force attacks. It includes automatic salt generation, a configurable cost factor, and produces a 60-character hash string containing the algorithm version, cost factor, salt, and hash. Bcrypt is recommended by OWASP, NIST, and most security authorities for password storage.
A parameter that controls bcrypt's computational cost. The actual number of iterations is 2^cost — so cost 10 means 1,024 iterations, cost 12 means 4,096 iterations. Higher cost factors make each hash slower to compute, directly increasing the time and hardware cost for an attacker attempting a brute-force attack. The cost factor should be periodically increased as hardware gets faster.
A 128-bit random value generated for each hash operation and embedded directly in the bcrypt output string. The salt ensures that identical passwords produce different hashes, defeating precomputed lookup tables (rainbow tables). Unlike external salting, bcrypt's salt is self-contained — the verification function extracts it from the hash string automatically.
A technique that applies a hash function multiple times (iterations) to make the computation deliberately slow. Bcrypt, scrypt, Argon2, and PBKDF2 all use key stretching. The purpose is to increase the cost of brute-force attacks: if each hash takes 100ms, testing 1 billion passwords would take over 3 years on a single CPU.
Bcrypt is a password hashing function designed by Niels Provos and David Mazières in 1999, based on the Blowfish cipher. Unlike fast hash functions (SHA-256, MD5), bcrypt is intentionally slow and includes built-in salting. This makes brute-force and rainbow table attacks impractical. OWASP recommends bcrypt as a top choice for password storage alongside Argon2 and scrypt.
The cost factor (work factor) determines the computational expense of hashing. Each increment doubles the time. Cost 10 takes ~100ms, cost 12 takes ~400ms. OWASP recommends a minimum of 10, with 12 being a good default for most applications. Choose a value where hashing takes 250ms–1s on your production hardware — slow enough to deter brute-force but fast enough for user login.
Bcrypt generates a random 128-bit salt for every hash operation. The salt is embedded in the output string (characters 8–29). This means the same password always produces a different hash — which is by design. To verify a password, use the Verify section which extracts the salt from the stored hash and recomputes.
No. All bcrypt hashing and verification runs entirely in your browser using the bcryptjs library. Your passwords never leave your device. The library is loaded from esm.sh CDN, but only the library code is downloaded — your input data stays local.
A bcrypt hash follows this format: $2b$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy. The parts are: $2b$ (algorithm version), 10$ (cost factor), the next 22 characters (Base64-encoded salt), and the remaining 31 characters (Base64-encoded hash). The total string is always 60 characters.
Common errors developers encounter and how to resolve them.
Hash generation takes too long: High cost factor performance Bcrypt's cost factor exponentially increases computation time. Cost 14 takes ~1.5 seconds, cost 16 takes ~6 seconds on a modern CPU. If hashing is too slow for your use case, lower the cost factor. For this browser-based tool, cost 12 or below provides a good balance. In production, benchmark on your actual server hardware and choose the highest cost factor that keeps login time under 1 second.
Verification fails for a correct password: Version prefix mismatch Bcrypt hashes have version prefixes: $2a$, $2b$, and $2y$. The $2a$ prefix is the original version, $2b$ fixes a bug in the OpenBSD implementation, and $2y$ is PHP-specific. Most bcrypt libraries accept all three prefixes interchangeably. If verification fails, check that the hash string is complete (exactly 60 characters) and has not been truncated by a database column that is too short.
Password exceeds 72 bytes: Bcrypt input length limitation Bcrypt only processes the first 72 bytes of input. For ASCII text, this means 72 characters; for UTF-8 text with multibyte characters, the limit may be fewer characters. Passwords longer than 72 bytes are silently truncated. If you need to support very long passwords, apply SHA-256 to the password first and then bcrypt the hash: bcrypt(sha256(password)). Most real-world passwords are well under 72 bytes.