Password Strength Checker — private, on-device
Entropy math + pattern detection + honest crack-time ranges. Your password never leaves this page — verify it in your network tab.
Quick answer: Check any password's real strength: entropy bits, crack-time estimates, and breach-pattern detection (common passwords, keyboard walks, repeats) — computed entirely on your device. Nothing is ever sent anywhere.
How to use
- Type or paste a password — watch the meter and the pattern flags.
About this tool
Strength = entropy: length × log2(alphabet size), minus penalties when patterns (dictionary words, '123456', keyboard rows like 'qwerty', doubled chunks) let attackers skip most guesses. This tool computes bits, translates to offline-crack time at 10 billion guesses/second (modern GPU rig), and flags the specific pattern that weakens you — all locally, so even this page never sees your secret.
FAQ
Is it safe to type my password here?
What's a good score?
Rate this tool
Your rating stays in this browser (local storage) — nothing is sent to any server.
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The complete password strength checker guide
Prefer the long version — a worked example, the mistakes people actually make, and answers to real questions? The blog guide Password Strength Checker — Complete Guide, Mistakes & FAQ covers all of it step by step.
Browse the collection: Generators — All 31 Free Online Tools
Key Facts
| Tool | Password Strength Checker — private, on-device |
| Category | Generators |
| Price | Free — no payment, no account |
| Data & privacy | Runs in your browser; inputs are not stored on our servers |
| Last updated | 2026-10-09 |
Sources & Further Reading
Official references for this category: NIST SP 800-63B (Digital Identity), MDN Web Docs.
This page is maintained by Tasleem Akhtar, Founder & Editor-in-Chief of Toolfyra, and was last reviewed on 2026-10-09.