Password Strength Checker
Check how strong your password is locally — entropy analysis, time-to-crack estimate, and zero data upload.
How ZeroData protects your privacy
- ✓ No Uploads: Processing happens entirely via client-side JavaScript.
- ✓ No Storage: We do not have a database. We physically cannot save your data.
- ✓ No Tracking: We don't log what you process or track your inputs.
- ✓ Verifiable: Check your DevTools Network tab. You will see 0 outbound requests.
How to Use the Password Strength Checker
- Type or paste a password into the input field.
- Watch the strength meter and grade update in real time.
- Review the breakdown: length, entropy, character types, and time-to-crack.
- Adjust your password until you reach 'Strong' or 'Very Strong' rating.
Frequently Asked Questions
Is my password sent to a server for analysis?
No. All analysis runs locally in your browser using JavaScript. Your password never leaves your device.
How is time-to-crack calculated?
We estimate based on 10 billion guesses per second, which represents modern GPU-based cracking speeds. The actual time depends on the attacker's hardware.
What entropy level is considered secure?
A password with 80+ bits of entropy is considered very strong. Most 16+ character passwords with mixed character types exceed this threshold.
Does this check against known breached passwords?
This tool focuses on mathematical strength analysis. For breach checking, consider using haveibeenpwned.com's API separately.
Related Tools
Hash Generator (Bcrypt/SHA)
Generate Bcrypt, SHA-256, and MD5 hashes locally. Never send passwords over the network.
Password Generator
Generate cryptographically secure passwords in your browser. No passwords are transmitted or stored anywhere.
Secret Scanner
Scan code and config files for leaked API keys, tokens, and secrets — entirely in your browser with zero uploads.
Bcrypt Hash Verifier
Verify bcrypt password hashes and generate new ones entirely in your browser. Your passwords never leave your machine.