Online Bcrypt password hashing tool: generate password hashes and verify passwords against hashes. Adjustable salt rounds, essential for authentication development.
TL;DR: Free bcrypt hash generator designed for password storage with built-in salt and adjustable cost factor. Computed locally in your browser, never uploaded.
For local tools, open DevTools → Network and search your input — it should not appear in requests.
Usage Guide
bcrypt is a password hashing function for storage — one-way, salted, and intentionally slow. This page generates bcrypt hashes and verifies a password against an existing hash using bcryptjs in your browser. Adjust cost (salt rounds) on a slider from faster/low to slower/harder. Use it for local integration tests and demos, not for pasting production user passwords onto a shared screen.
1. Hash and verify
Hashing runs synchronously via bcryptjs after a short yield so the UI can show a busy state. Higher rounds mean noticeably longer waits — that cost is the point for online guessing resistance.
- Enter a password (show/hide toggle available), set salt rounds, and generate a hash.
- To verify, paste a candidate password and an existing hash into the verify section and compare for match / no-match.
2. Hashing is not encryption
You cannot decrypt a bcrypt hash back to the password. Forgotten passwords are reset, not “reversed.” If a tutorial promises decrypting bcrypt, it is wrong or talking about a different primitive. Store only hashes server-side; never log raw passwords alongside them.
3. Choosing cost (rounds)
Too low and offline attacks get cheaper; too high and login endpoints burn CPU. Libraries publish era-appropriate defaults — re-benchmark when hardware or threat models change. This UI exposes rounds 4–14 so you can feel the latency tradeoff on your machine before baking a value into server config.
- Do not treat bcrypt as reversible encryption.
- Load-test login with the chosen cost on production-like hardware.
- Never demonstrate with real customer passwords.
4. Salts and formats
Each bcrypt hash embeds its salt and cost. You normally do not prepend your own salt string unless you know exactly why. Verify must use the full hash string your application stored. Truncating the hash or rewriting the cost prefix by hand is a common self-inflicted mismatch.
5. Migrating from legacy hashes
Systems still storing MD5 or plain SHA for passwords should plan an upgrade-on-login path to bcrypt or argon2 — generating sample bcrypt strings here does not migrate a database by itself. Dual-verify during transition: accept legacy hash once, re-hash with bcrypt, then drop the legacy path.
6. Privacy and demo hygiene
Computation is local, which reduces accidental upload risk, but shoulder surfing and screen recordings remain. Use throwaway passwords in demos. Clear the fields when you finish. Pair with the password generator for strong test secrets and the strength checker for policy education — hashing stores secrets; it does not invent good ones.
7.
Library dialect differences are rare but real — one successful verify in your language binding beats assuming wire compatibility.
- Generate a hash at the cost your server will use.
- Verify success with the same password and failure with a one-character change.
- Confirm your application’s bcrypt library accepts the $2a/$2b-style string this page emits.
8. Test data, peppers, and cost changes
Seed environments need stable passwords with known hashes. Generate once at the agreed cost, store hash plus plaintext in a secrets manager for QA only, and rotate when people leave the team. Do not copy production password hashes into browser tools for debugging login — that spreads credential material into clipboard histories. Offline attackers who steal a hash dump will try GPU-accelerated guessing; cost buys time, not immortality. Combine with breach detection, lockouts, and MFA. If your framework wraps bcrypt with a version prefix or pepper, verify using the framework helpers even when this page’s raw hash looks familiar. Raising rounds later means new hashes use the new cost while old rows remain valid until re-login upgrades. Plan a metric for percent of rows still on the old cost. You cannot bulk-rehash offline without plaintext. Communicate downtime expectations if you force global resets instead of lazy upgrades.
- Keep QA plaintext passwords in a secrets manager, not in git.
- Never paste production hash dumps into the browser for curiosity.
- Re-verify through framework helpers when peppers or wrappers exist.
FAQ
No. bcrypt is a one-way hash — the output cannot be decrypted back to the original, so a forgotten password can only be reset. There is no such thing as "reverse bcrypt".
The default of 10 suits most cases, and each increment doubles the computation time. Too low invites brute force; too high drags down your login endpoint. Benchmark on your own hardware and pick a value in the 10-12 range; the tool supports custom values.
No. bcrypt embeds its salt in the hash already — do not concatenate your own plaintext salt unless you fully understand the consequences, as it can break what the algorithm expects.
Yes. Paste an existing bcrypt hash together with a candidate password and the tool checks whether they match — handy for troubleshooting credentials during development and integration work.
Plan an upgrade path that re-hashes credentials with bcrypt or argon2 at login time, instead of only demoing converted samples on this page. Migration has to happen in your business code; this tool just generates and verifies samples.
No. Local computation still cannot stop shoulder surfing, screen recording, or screen sharing — use fake passwords for tests and keep real credentials in a proper vault and signup flow.
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