bcrypt playground

Generate and verify bcrypt hashes right in your browser. Everything runs locally, fully self contained, works offline. Nothing is ever sent anywhere.

Generate a hash

Password

Cost factor (work factor)

cost = 10 → 2¹⁰ = 1024 key rounds

Algorithm version

Hash anatomy

prefix — version identifier

cost — work factor (2^cost rounds)

salt — 22 chars (128-bit, base64)

hash — 31 chars (184-bit digest)

Verify a password against a hash

Password to test bcrypt hash

Tip: generate a hash above, then paste it here (or hit "Verify") to see a match. Change one character of the password to see a no-match.

Why bcrypt?

Fast general-purpose hashes like MD5 or SHA-256 are the wrong tool for passwords: an attacker with a stolen database can try billions of guesses per second on a GPU. bcrypt is deliberately different.

Deliberately slow. The cost factor sets an exponential work factor (2^cost key-setup rounds). Bump the cost by one and every guess costs twice as much. You tune it so a single hash takes a fraction of a second for you, but brute force stays painful for attackers.
Per-password salt. A random 128-bit salt is generated and embedded in the output, so identical passwords produce different hashes and precomputed rainbow tables are useless.
Adaptive. As hardware gets faster, raise the cost. Old hashes keep working; new ones get heavier. The cost lives inside the hash string itself.
Self-contained format. The version, cost, salt, and digest all travel together in one $2b$... string, so verification needs nothing but the stored hash and the candidate password.

What's the difference between $2a$ and $2b$?

Both are the same Eksblowfish algorithm. $2a$ is the classic prefix. $2b$ was introduced by OpenBSD to fix a wrap-around bug that only affected passwords longer than 255 bytes; for normal passwords the two are identical. There are also $2y$ (a PHP-specific tag) and the legacy $2$. This playground computes the digest the same way for both toggles and just writes the prefix you pick.