Password Strength Checker

Security & Entropy Analyzer

Analyze password strength, entropy bits, brute-force crack time, common pattern vulnerabilities, and get security tips in real time

100% Client-Side Privacy: Your password is evaluated entirely inside your web browser. No characters are ever stored, transmitted, or logged over any network.

Enter Password to Check

Test sample passwords:

Overall Strength

Very Weak0/100

Entropy

0 bits

Very WeakWeakFairStrongVery Strong

Length

chars

Charset Pool

possible chars

Security Grade

Low

entropy class

Brute Force Crack Time

Estimated time for different attacker hardware to guess this password:

Online Web Form

100 guesses / sec (rate-limited)

0 seconds

Distributed Botnet

10,000 guesses / sec

0 seconds

High-End GPU Rig

100 Billion guesses / sec

0 seconds

Supercomputer Cluster

100 Trillion guesses / sec

0 seconds

Security Checklist

At least 12 characters (16+ recommended)

Longer passwords grow search space exponentially.

Lowercase letters (a-z)

Expands pool by 26 characters.

Uppercase letters (A-Z)

Expands pool by 26 characters.

Numbers (0-9)

Expands pool by 10 characters.

Special symbols (!@#$%...)

Expands pool by up to 33 characters.

No repeated or sequential patterns

Repetitions weaken practical entropy.

Vulnerabilities & Suggestions

No known pattern vulnerabilities or dictionary sequences detected.

How to Improve

Type or generate a password to inspect its security score.

What is Password Entropy?

Entropy measures how unpredictable a password is in units called bits. Calculated using Shannon entropy formula:

Entropy = Length × log₂(Character Pool Size)

EntropyStrength LevelAttack Resistance

< 28 bitsVery WeakCracked in seconds

28 – 35 bitsWeakCracked in minutes

36 – 59 bitsModerateVulnerable to GPU rigs

60 – 79 bitsStrongCenturies offline

80+ bitsMilitary GradeImmune to brute force

Passphrase vs. Complex Password

Many people think adding symbols to an 8-character word like Tr0ub4dor&3 makes it safe. In reality, length is far more important than complexity!

Short Complex Password (e.g. "P@ss12")

6 characters · ~32 bits of entropy · Crackable in seconds with modern GPUs.

Multi-Word Passphrase (e.g. "correct-horse-battery-staple")

28 characters · ~80+ bits of entropy · Easy for humans to remember, impossible for computers to brute force!

Tip: Always use a reliable password manager like Bitwarden or 1Password to store unique credentials for every account.

What is Password Strength Checker?

The Password Strength Checker is a privacy-first security tool that evaluates the strength, entropy, and crack resistance of your passwords in real time. It calculates information entropy, estimates brute-force crack times across modern attack hardware, flags common patterns and dictionary vulnerabilities, and provides actionable recommendations to make your credentials unbreakable.

How to Use Password Strength Checker

Enter or Paste Password

Type or paste your password into the input field. Processing occurs 100% locally in your browser — nothing is sent across any network.

Review Strength Score

Check the visual strength meter, entropy score (in bits), and estimated crack time for different brute-force scenarios.

Examine Checklist & Diagnostics

Inspect the criteria checklist (length, lowercase, uppercase, numbers, symbols) and scan for sequential or repetitive patterns.

Optimize and Strengthen

Apply the recommendations or use the one-click generator to create a robust, high-entropy alternative.

Key Features

Real-time password strength scoring and meter

Shannon entropy calculation in bits with character pool breakdown

Brute force crack time simulation (online, GPU rig, supercomputer)

Vulnerability detection (common words, keyboard walks, repeated characters)

Instant password generator and passphrase recommendations

100% client-side privacy guarantee — zero network requests

Tips & Best Practices

1
Aim for at least 16 characters or use a multi-word passphrase for maximum security.
2
Combine uppercase, lowercase, numbers, and special symbols to dramatically expand entropy.
3
Never reuse the same password across multiple online accounts or services.
4
Use a reputable password manager to store complex credentials securely.

Why Use Our Online Password Strength Checker?

Password Strength Checker gives developers a fast, distraction-free utility that runs entirely client-side. No accounts, no data sent to any server, no extensions to install. Paste your input, get your output, copy to clipboard — designed to slot into your daily workflow without breaking your flow.

Client-SideCode stays private

Zero SetupNo installs needed

Copy to ClipboardOne-click workflow

Open StandardsCommon formats

Frequently Asked Questions

Is it safe to test my real password here?

Yes, 100%. The Password Strength Checker operates entirely within your browser's JavaScript engine. No data is stored, logged, or transmitted over the internet.

How is brute force crack time calculated?

Crack time is computed by calculating the total search space (character pool size raised to the power of length) and dividing by realistic attack speeds, from standard online rate-limited logins to high-speed offline GPU cracking rigs capable of hundreds of billions of hashes per second.

What is password entropy and why does it matter?

Password entropy measures the unpredictability of a password in bits. Higher entropy means more guesses are required to crack it. Generally, 60+ bits is considered strong, and 80+ bits provides military-grade resilience against modern cracking rigs.

Why are length and passphrases better than short complex passwords?

Exponential growth in length increases the search space far more rapidly than adding symbols to a short password. A 20-character passphrase of 4 random words is both easier to remember and much harder for computers to brute-force than an 8-character complex string.

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