Strong Password Generator
Generate cryptographically secure passwords with customizable length and character sets. Runs entirely in your browser — passwords never leave your device.
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How this password generator works
Every password is built from the character sets you pick — lowercase, uppercase, digits, and symbols — using window.crypto.getRandomValues, the browser's cryptographic random-number generator. Unlike Math.random, this source is designed to produce values suitable for keys and passwords. To avoid modulo bias, the generator samples random bytes and discards values that would introduce skew before mapping them to the pool.
How to pick a strong password
- Length beats complexity. A 20-character lowercase password is harder to crack than an 8-character mixed one.
- Use a password manager. Don't try to memorize unique passwords for dozens of sites — let 1Password, Bitwarden, Apple Passwords, or your browser store them.
- Unique per site. The single biggest risk is reuse — one data breach compromises every account that shares the password.
- Enable 2FA. Even a strong password is safer when combined with a second factor.
Understanding entropy
The entropy number under your password is log₂(alphabet^length) — roughly "how many random bits this password represents." A rough guide:
- < 40 bits — weak, crackable in minutes to hours with modern hardware.
- 50–70 bits — reasonable for everyday accounts behind rate limits.
- 80+ bits — strong against offline attacks on leaked hashes.
- 128+ bits — overkill for any single password; use for encryption keys.
Privacy
No generated password is ever transmitted, logged, or stored. You can disconnect from the internet and this tool will still work. Close the tab and the password is gone — copy it somewhere safe first.