Password Strength Analyzer
Analyze password complexity, compute entropy, estimate cracking time, and generate strong, cryptographically secure passwords locally.
1. Test Password Strength
This password is in common use.
Add another word or two.
Estimated Crack Times
2. Secure Password Generator
Options
What is Password Entropy?
Password Entropy is a mathematical measurement of the unpredictability of a password. It is calculated in **bits**. The higher the entropy (bits score), the more guesses a computer requires to crack it via brute-force. A password with **80 bits of entropy** or more is generally considered military-grade and secure against modern offline password cracking rigs.
How our Strength Checker Works
Unlike simple calculators that only count characters, this tool uses the Dropbox-designed **`zxcvbn`** library. `zxcvbn` uses a smart heuristics engine matching against 30,000 common passwords, names, patterns (like sequences, keyboard spatial paths, and dates). This gives a highly realistic estimation of cracking times and provides actionable warnings (e.g. "this is a common name", "avoid keyboard patterns"). Everything runs 100% locally in your web browser for complete safety.
How to Create a Strong Password
Rule 1: Length Beats Complexity. A 16-character password of simple lowercase words (e.g., `correcthorsebatterystaple`) has far higher entropy and is much harder to crack than a short complex password like `P@$$w0rd` (which is easily guessed by dictionary scanners).
Rule 2: Avoid Common Patterns. Do not use calendar years (e.g. `2024`), sequential runs (`abcdef`), or common word substitutions (`3` for `e`, `1` for `i`).
Rule 3: Use a Password Generator. Standard human brains are bad at creating true randomness. Use our cryptographically secure password generator to output completely random sequences.