Password Strength Checker
Test how strong your password really is - entropy analysis, estimated crack time, and concrete improvement suggestions. Powered by Dropbox's zxcvbn library, the gold standard for password strength estimation.
Issues Found
- No password yet
How to Improve
- Suggestions appear here
Most Passwords Are Cracked in Seconds
Modern attackers don't guess passwords character-by-character - they use rainbow tables, leaked-credential databases, and dictionary attacks running at 100+ billion guesses per second on commodity GPUs. A "strong-looking" password like P@ssw0rd1! is in every cracker's wordlist and falls in under a second. This tool uses zxcvbn, the algorithm Dropbox built and open-sourced in 2014, which simulates real attacker strategies (common patterns, leetspeak substitutions, keyboard walks, dictionary words, dates) - giving you a realistic crack-time estimate, not a naïve "complexity score".
Credential Stuffing
Once a password leaks from one site, attackers try it on every site you might use. ~3.6 billion credentials are circulating in public breach databases right now.
GPU Cracking Speed
A single $1,500 GPU can test 100B+ password hashes per second. A cluster of 8 GPUs cracks any 8-char password (any character set) in under 12 hours.
Pattern Attacks
Capital letter at start, number/symbol at end, common word in middle - that pattern is in every cracker's playbook. Naive complexity rules guarantee compliance, not security.
Test a Password in 3 Steps
Type or Paste the Password
Enter the password you want to test. The strength meter and crack-time estimate update in real time. Nothing is transmitted - open your browser's Network tab to verify. The eye icon toggles visibility if you need to see what you typed.
Read the Score & Crack Time
The score is 0–4 (Very Weak → Very Strong). The crack-time estimate is based on a 100 billion guesses/second offline attacker - the realistic threat model. Green is what you want; orange means you should not use this password for anything important.
Apply the Suggestions
The right panel shows specific improvements - e.g., "All-lowercase passwords are easy to crack" or "This password is in 23 known data breaches". Apply them, retest, repeat. For high-value accounts, aim for score 4 with 60+ bits of entropy.
Who Should Use This Tool
Anyone Setting a New Password
Banking, email, work accounts, password manager master password - test before you commit. A 30-second check now saves hours of incident response later.
Developers Building Auth
Use the tool to validate your password-policy design. Most "8 chars + 1 number" rules let through trivially weak passwords. Embed zxcvbn in your signup form for real protection.
IT & Security Teams
Audit critical passwords (admin, root, service accounts). Justify password-policy improvements with concrete crack-time numbers your CFO understands.
Security Trainers & Educators
Show users in real time what a strong password actually looks like. The crack-time changes from "2 seconds" to "centuries" with one well-placed change - the most teachable security demo there is.
Regulated Businesses
Banking (SAMA, RBI), healthcare (HIPAA, KSA PDPL), and SaaS auditors increasingly require evidence of password-strength enforcement. This tool generates ad-hoc evidence for audits.
Password Manager Migrators
Switching managers? Use the tool to identify weak entries during migration. Auto-rotate weak ones into long generated passwords before re-encrypting.
Frequently Asked Questions
No. The entire tool runs in your browser using the open-source zxcvbn library. Your password never leaves your device - no API call, no analytics, no logging. Confirm by opening your browser's developer Network tab while typing.
zxcvbn is a password-strength estimator written by Dan Wheeler at Dropbox in 2014. Unlike naive "1 number + 1 symbol" rules, it simulates real attacker strategies: known dictionaries, leetspeak substitutions, keyboard patterns, dates, repeats, and credential-database matches. It's now the gold standard used by 1Password, Bitwarden, and most security-conscious services.
Entropy (bits) is a mathematical measure of randomness - 60 bits means roughly 2^60 possible combinations. The zxcvbn score (0-4) is a practical estimate after factoring in known patterns, dictionaries, and substitutions, so a "60-bit" password can score lower if it follows predictable patterns. Both are useful: entropy for theoretical strength, score for real-world strength.
It assumes an offline attacker with a fast hardware setup - 100 billion guesses per second, which is what an 8-GPU cluster running Hashcat against unsalted MD5 can deliver. For salted bcrypt or Argon2, the rate is much slower, so the displayed crack time is conservative for properly-hashed passwords. For credential stuffing (online attacks), the rate is throttled to ~1000 guesses/second, where even a moderate password lasts decades.
For typical use: score 3 with 50+ bits of entropy. For high-value accounts (email, banking, password-manager master): score 4 with 65+ bits. The simplest way to hit either: a 4-word random passphrase (like the famous "correct horse battery staple" example) gives ~50 bits with 0 effort to memorize. Add a number or symbol for higher.
No - use this with a password manager. The manager generates and stores the password; this tool is for spot-checking the result, validating master passwords, and educating users. Never reuse passwords across sites; the manager makes that practical.
Because every password cracker in the world has it in their first 100 attempts. Common substitution patterns (a→@, o→0, i→1) plus a familiar word add zero security against modern dictionary attacks. The score reflects what a real attacker would do, not what a checkbox-only "complexity" rule would accept.
Need a Full Cybersecurity Audit?
Password strength is one of dozens of security controls. Brainguru runs full security audits - penetration tests, security-headers analysis, OWASP Top 10 reviews, NCA / SAMA framework alignment for GCC clients. From single-engagement audits to ongoing security retainers.
