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Password Strength Checker

See how fast a password could be guessed, which patterns give it away, and how to make it stronger, fully offline.

Free, no uploads, no sign-up. Runs 100% in your browser.

How Password Strength Checker works

Uses zxcvbn, which looks for dictionary words, names, keyboard patterns, dates, repeats and leet speak, then estimates guesses and crack times for online and offline attacks. Everything runs in this tab.

How to use Password Strength Checker

1. Open Password Strength Checker and paste or type your input.
2. Results update instantly as you type.
3. Tweak options such as format, indentation or algorithm.
4. Copy the output or download it as a file.

Tips

• Everything is computed locally. Safe for tokens, keys and private data.
• Use Ctrl/⌘ + K to jump between developer tools quickly.

Password Strength Checker FAQ

Are my files uploaded?

No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.

Is it free? Are there limits or watermarks?

Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.

Does it work offline?

Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

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• Shamir Secret Sharing: Split a password or seed phrase into shares so any 3 of 5 (or any k of n) can rebuild it, with QR codes.
• JSON Formatter: Prettify, validate, minify and explore JSON as a tree.