Password Strength Checker

How to use the Password Strength Checker

1. Type or paste a password into the box. The analysis updates as you type — nothing is sent anywhere.
2. Read the strength label and the entropy figure in bits. More bits means exponentially more guesses.
3. Scan the crack-time table: an offline GPU attack is millions of times faster than a login form.
4. Work through the "What we found" list — every warning is a concrete weakness an attacker can exploit.
5. Fix the weaknesses, or generate a random password instead, then verify it has never been breached.

Why use ZillaKit's Password Strength Checker?

Most strength meters you meet on signup forms are theatre: they count character types, see one capital letter and one exclamation mark, and cheerfully call "Passw0rd!" strong. Real attackers do not brute-force blindly — they start with leaked password lists, dictionary words, names, dates, keyboard walks and predictable substitutions (a to @, o to 0, i to 1). This checker models that reality. It calculates true entropy from the character pool and length, then penalises the patterns crackers exploit first: appearing in the top common-password list, repeated characters, sequential runs, keyboard walks like "qwerty" and "asdfgh", years and dates, and leetspeak versions of dictionary words. It then converts the result into guesses needed and shows how long that takes at five realistic attack speeds — from a rate-limited login form to a purpose-built GPU cluster. Everything runs client-side in your browser: the password is never transmitted, never logged and never stored, and the page makes no network requests at all while analysing. It is free, needs no signup, and works offline once loaded.

What counts as a strong password in 2026?

The honest answer is length plus randomness. A 16-character random password drawn from letters, digits and symbols carries roughly 100 bits of entropy — far beyond what any current or foreseeable hardware can exhaust. A four-word random passphrase such as "candle-plaza-driftwood-mint" is easy to remember, easy to type on a phone, and still lands around 50-60 bits, which is enough for most accounts when paired with two-factor authentication. What does not work is a short password made complicated: "T1g3r!" looks fierce and dies in under a second against a GPU, because "tiger" is in every dictionary and the substitutions are the first ones attackers try. Aim for 14+ characters, never reuse a password across sites, and let a password manager remember them for you.

FAQ

Is my password sent anywhere?

No. The analysis is pure JavaScript running in your browser tab. This page makes zero network requests with your input — you can confirm it in your browser's network tab. Nothing is stored in localStorage either.

What is entropy, in bits?

Entropy measures unpredictability. Each additional bit doubles the number of guesses an attacker needs. 40 bits is about a trillion guesses (weak against offline attacks), 60 bits is around a quintillion (reasonable), and 80+ bits is comfortably out of reach of current hardware. The figure shown here is reduced when we detect predictable patterns, because those patterns shrink the real search space.

Why do the crack times differ so much between rows?

Because the attack matters more than the password. Guessing against a live login form that rate-limits you might allow 100 attempts an hour. If an attacker steals a password database instead, they can guess offline — billions of times per second on consumer GPUs if the site hashed passwords badly, or a few thousand per second if it used a slow hash like bcrypt or Argon2. The same password can be "centuries" in one row and "instant" in another.

The tool says my password is strong, but is it actually safe?

Strong is not the same as unbreached. If you used that password on a site that later got hacked, its strength is irrelevant — it is on a list. Run it through our Password Breach Checker, which uses k-anonymity so the password never leaves your device.

Does adding "!" at the end help?

Barely. Cracking tools apply "append a symbol", "capitalise the first letter" and "add a year" rules automatically to every dictionary word. A single predictable symbol at the end adds a fraction of a bit against a real attacker. Length and randomness are what move the needle.

Are passphrases better than passwords?

Random passphrases are excellent — but they must be random. Four words picked by a computer from a large word list are strong. Four words from a song lyric or a familiar phrase are not, because attackers run phrase dictionaries too.