Password strength
Rough entropy and common-pattern warnings in the tab. Nothing's sent.
Runs in this tab. The file stays here.
This runs in your browser. Nothing is uploaded.
About Password strength
Estimates password entropy and flags common patterns in your browser. Nothing is checked against an online breach list.
Online strength meters that 'helpfully' check your password against a remote API are asking you to type the secret into someone else's box. This one never leaves the tab. It guesses entropy from length and character mix, then nags about short strings, runs of the same character, keyboard walks, and tired fragments like password or qwerty.
Treat the score as a rough ceiling, not a certificate. Four ordinary words can beat a short symbol salad, and this page is too dumb to know that. A green label also doesn't mean the password is absent from every breach dump, I won't phone Have I Been Pwned with your string to find out.
Use it while you're drafting something for a manager. On a shared machine, close the tab when you're done. The field is still just memory.
How to use Password strength
- 1Type or paste the password into the side panel field.
- 2Read the label, bit estimate, and any warnings.
- 3Adjust the password until the warnings clear, then store it somewhere other than this page.
What it won't do
- Heuristic only, no breach API, no zxcvbn dictionary dump.
- Does not replace a password manager.
Common questions
Does password strength check against known breaches?
No. That needs a network call against somebody else's corpus. Useful elsewhere; deliberately absent here so the string never leaves the machine.
What does the bit estimate mean?
Length times log2 of the character pool it thinks you used. That math assumes random independent characters. People don't type like that, so the number is optimistic, treat a high score as 'maybe fine', not 'proven safe'.
Is the password visible to the page after I leave?
Only while this tab still has it. Refresh or close and it's gone. There's no history on a server because there's no server in the loop.
Related tools
Why this one doesn't upload your file
There is no server to upload to. This page is a static file, and the work happens in your browser using the same graphics and WebAssembly code that renders every other site you visit. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network entirely and it keeps working. The longer explanation