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Password Strength Checker — free online tool

Estimate entropy and optionally check against public breach lists (k-anonymity) before adopting a new master password.

Useful when you want a quick answer without pasting sensitive data into random chat bots.

How to use Password Strength Checker

  1. Type a password into Password Strength Checker (use a test password, not a real one you rely on).
  2. Read entropy estimate and checklist feedback on the card.
  3. Optionally run the breach check if enabled—it sends only a hash prefix.
  4. Clear the field after testing; do not leave production passwords in the tab.

Practical tips

  • Test a throwaway password with the same length and symbol mix as your real one before adopting it.
  • Run the optional breach check only after you are comfortable with the hash-prefix (k-anonymity) method.
  • Pair with the Password Generator when you need a fresh random string, then score it here.

Example

Type a 16-character test passphrase to read entropy hints, then run the optional HIBP prefix check.

Related tools on Webtoolshop

  • Password Generator — Create a long random password, then score it here before you save it.
  • Hash Generator — Generate SHA-256 or other digests for developer workflows—not for storing passwords.

Limitations

Password Strength Checker runs on text in your tab only—there is no cloud save, version history, or collaboration. Copy results before closing the page.

Privacy & data

We do not run a database on this static site. Text and generated output exist only in your tab until you close or refresh the page.

Frequently asked questions about Password Strength Checker

Is it safe to type my real password into Password Strength Checker?

The estimate runs locally in your browser. Optional HIBP breach check sends only the first five characters of a SHA-1 hash—never the full password. Still, use a similar test password if you are cautious, then apply rules to your real one offline.

What does the Have I Been Pwned check do?

It queries the public HIBP range API with a hash prefix (k-anonymity). Your full password is not transmitted. A hit means the password appeared in known breach dumps—pick a different one.

Does Webtoolshop store text I paste into the Password Strength Checker?

We do not run a database on this static site. Text and generated output exist only in your tab until you close or refresh the page.

Password Strength Checker

Length & character-set estimate — optional Have I Been Pwned check (SHA-1 prefix only).

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