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Password strength checker

Score a password with zxcvbn, Dropbox's guessing model, and see exactly which dictionary words, repeats, or patterns an attacker would play first. The dictionaries load on first run; the password never leaves the tab.

Password
Dictionaries (common words, english, passwords) load lazily on first score
Personal words

Fed to the model as user-input dictionary entries: they demote passwords built from them. Kept in memory only.

names, pets, streets, employers. Words an attacker who knows you would try first (plan 04 CRYPTO-4)
What this tool does not do
  • No breach-database check: that needs a third-party k-anonymity request (rejected by plan); zxcvbn knows common passwords from its bundled list only.
  • The password lives in this tab’s memory while you type. Nothing is sent or stored, and a browser tab cannot guarantee the memory is zeroized after.
  • A strong score on this page does not make a password right for your site. Length, uniqueness per site, and how you store it matter more.
Paste, drop, or type to begin. Everything stays on this device.