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Bcrypt & Argon2 Generator

Hash a password with bcrypt or Argon2 and verify a password against an existing hash. Tune the cost factor, memory, iterations and parallelism, see how long the hash takes, and read the parsed parts of any hash you paste.

Everything runs locally in your browser. Your data never leaves your device.

Password

The password stays in this field and is not saved anywhere.

Parameters

4,096 rounds

4 to 31

Each step doubles the work: cost 12 runs 4,096 rounds. OWASP recommends at least 10, and 12 is a common default.

Hash

Type a password above, then press Generate hash.

Which algorithm to pick

Argon2id is the first choice for new systems and what OWASP recommends. It combines Argon2i's defense against side channel attacks with Argon2d's resistance to GPU cracking. bcrypt remains acceptable for existing systems at cost 10 or higher, but it only reads the first 72 bytes of a password. Argon2i and Argon2d are the specialized single purpose variants, useful only when a spec demands one.

Next steps

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About the Bcrypt & Argon2 Generator Tool

This tool hashes a password with bcrypt or Argon2 and checks a password against a hash you already have. Pick the algorithm, tune its work factor, and press generate. The result is the standard encoded string, $2b$12$... for bcrypt or $argon2id$v=19$m=19456,t=2,p=1$... for Argon2, ready to paste into a database seed, a config file or a test fixture.

Every run draws a fresh random salt, so the same password gives a different hash each time. The tool reports how long the hash took, which is the honest way to judge a work factor: slow enough to hurt an attacker, fast enough for your login flow. A hash inspector breaks any pasted hash into its parts, and the verify mode tells you whether a password matches it.

What you can do

  • Generate a bcrypt hash with a chosen cost factor.
  • Generate an Argon2id, Argon2i or Argon2d hash with tunable memory, iterations, parallelism and digest length.
  • Verify a password against an existing bcrypt or Argon2 hash.
  • Apply the OWASP recommended Argon2 configurations with one click.
  • See how long a hash takes as a feel for the work factor.
  • Decode an encoded hash into its algorithm, parameters, salt and digest.
  • Check which algorithm and cost a stored hash uses.

How to use the Bcrypt & Argon2 Generator

  1. 1Type or paste the password. Use the eye button to reveal it while typing.
  2. 2In generate mode, pick bcrypt or an Argon2 variant and adjust the parameters. The defaults follow the OWASP recommendations, and warnings appear when a choice falls below them.
  3. 3Press Generate hash and copy the encoded result. Press New salt to rehash the same password with a fresh salt.
  4. 4To check a password, switch to verify mode, paste the stored hash, and press Verify password. The algorithm is detected from the hash itself.

What the encoded string contains

Password hashes carry everything needed to verify them later. A bcrypt hash like $2b$12$... packs the format variant, the cost factor, 22 characters of salt and 31 characters of digest into one string. An Argon2 hash spells its parameters out: m is the memory in KiB, t the iterations and p the parallelism, followed by the salt and digest in base64. The hash inspector labels each of these parts for any hash you paste or generate, which helps when auditing what an existing system actually stored.

Choosing the work factor

For bcrypt, each cost step doubles the work, so cost 12 runs 4,096 rounds and cost 13 twice that. OWASP recommends a cost of at least 10. For Argon2id, OWASP recommends 19 MiB of memory with 2 iterations and 1 lane as a minimum, and lists equivalent trades of more iterations for less memory, all available here as presets. The reported hashing time makes the trade concrete. Something around 100 ms per hash is a common target for login flows.

bcrypt has one quirk worth knowing: it only reads the first 72 bytes of a password. The tool warns when a password crosses that line. Argon2 has no such limit.

Generating test data

A common use is seeding a development database or writing tests for a login flow. Create a throwaway password with the Password Generator and send it here, hash it, and paste the encoded string into your fixture. For general purpose digests like SHA-256, which are not suitable for storing passwords, use the Hash Generator instead.

Credits

Open source does the heavy lifting in this tool. Thank you to:

  • hash-wasm

    Hand-tuned WebAssembly implementations of MD5, SHA, BLAKE, bcrypt, Argon2 and many more.

Everything this site builds on is listed on the credits page.

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