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Password Strength + Breach Checker

Live strength meter + k-anonymity check against the Have I Been Pwned password database. Your password never leaves your device.

By Daniel BeglaryanUpdated August 2026

PrivateNo Account

Your password never leaves your browser. We hash it locally with SHA-1, send only the first 5 hex characters to Have I Been Pwned, and compare the suffix list locally (k-anonymity).

Deep dive

About Password Strength + Breach Checker.

Check Password Strength + Breach Exposure — Privately

CipherForces Breach Checker does two things: scores your password's strength locally (entropy + pattern penalties), and checks against the Have I Been Pwned password database using k-anonymity so we never see your password. The first 5 characters of the SHA-1 hash are sent to the HIBP API; the remaining 35 characters never leave your device. HIBP returns ~500 hash suffixes that share the same prefix, and we match locally.

What the Strength Meter Catches

Charset entropy (bit count of the password's randomness)
Top-100 leaked passwords (qwerty, password123, etc.)
Keyboard runs (qwerty, asdf, zxcv)
Sequential digits + letters (12345, abcde)
Repeated characters (aaaa, 1111)
Year-only patterns (1990, 2024)
Leetspeak normalization (P@ssw0rd → password)

Score

0 (Critical) → 1 (Weak) → 2 (Fair) → 3 (Strong) → 4 (Excellent). The breach check is independent — even a "strong" password can show up as breached if it's been leaked elsewhere.

Privacy: Your password never leaves your device. The HIBP k-anonymity API exchange uses a 5-character hash prefix only.

FAQ

Frequently asked questions.

Does my password get uploaded when I use this breach checker?

No. Your password never leaves your device. The tool hashes it locally with SHA-1, then sends only the first five characters of that hash to the Have I Been Pwned range API. The full password and full hash stay in your browser, so nobody can read or store what you typed.

How do I check if my password was found in a data breach?

Type your password into the tool. It instantly shows a live strength meter and runs a k-anonymity lookup against the Have I Been Pwned password database. If your password appears in known breaches, you will see it flagged so you know to stop using it and pick a new one.

What is the k-anonymity method this password checker uses?

K-anonymity lets you check a password without revealing it. Your password is hashed locally, and only the first five hash characters are sent to Have I Been Pwned. The service returns many matching hash suffixes, and the comparison happens in your browser, so your actual password stays private.

Is this password strength and breach checker free to use?

Yes. The tool is completely free with no signup and no account required. Everything runs client-side in your browser, so there is nothing to install and no file or password is uploaded to a server. You can check as many passwords as you want, privately and at no cost.

Three steps