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Password Strength Tester

Check how strong a password really is: entropy estimate, 0–4 strength score, crack-time estimates, and a checklist of weak patterns (common passwords, repeats, sequences, keyboard rows). Runs entirely in your browser.

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—Start typing to analyze
This tool runs entirely in your browser — the password never leaves the page. The estimate uses a length-and-complexity entropy model with penalties for common passwords and weak patterns; it is a heuristic floor, not a guarantee. Always check your password against a breach database and store it in a password manager. Pair it with the Password Generator for random credentials, and the Secret Scanner to catch hardcoded credentials before they land in a repo.

What is Password Strength Tester?

Password Strength Tester analyzes a password the way an attacker would think about it: it estimates entropy in bits (length × character-pool size), then applies explicit penalties for the patterns that make passwords weak in practice — matches against a curated list of the most commonly breached passwords, repeated characters, sequential runs like abc or 123, and keyboard rows like qwerty. The result is a 0–4 strength score, crack-time estimates for four attack scenarios (throttled online, unthrottled online, offline slow hash, offline fast hash), and a checklist of exactly which checks your password passes or fails. All analysis runs in your browser; the password never leaves the page.

Common Use Cases

Auditing Existing Passwords

Paste a password you currently use (or a candidate) and see precisely why it is weak — length, missing character classes, a breached-list match, or a pattern — before you commit to it.

Testing New Account Setups

When setting up credentials for a new service, quickly verify the password meets your own strength bar rather than just the service's minimum requirements.

Security Reviews & Demos

Show stakeholders why "complex-looking" passwords like Tr0ub4dor&3 are still weak and what a genuinely random passphrase looks like.

QA of Password Rules

Validate your product's password policy against real entropy: check that the minimums you enforce actually produce strong passwords, not just compliant ones.

How to Use This Tool

  1. Type or paste a password into the input — analysis updates live as you type
  2. Read the 0–4 score and the entropy figure (in bits) with the pattern penalty called out
  3. Check the estimated crack times for the four attack scenarios
  4. Review the pass/fail checklist and the concrete suggestions for weak spots
  5. Click "Copy analysis" to paste the result into a ticket, review, or report

Related Tools

Password Generator → Secret Scanner → HMAC Generator →

Learn More

Password Strength Tester is a free online tool that requires no signup or installation. It works directly in your browser, keeping your data private and secure.