Password Strength Checker
Check password strength and get improvement suggestions
How to Use Password Strength Checker
- Open Password Strength Checker above — it loads instantly, no signup or download required.
- Provide your input (paste text, drop a file, or type directly into the tool).
- Get your result instantly — everything is processed locally in your browser and nothing is uploaded.
- Copy or download the output. Refresh the page to clear all data from memory.
About Password Strength Checker
What this page solves
Every "how strong is my password" site on Google asks you to type your real password into a remote form — the exact opposite of what you should do. This checker scores strength locally using the same zxcvbn model 1Password and Dropbox use, and never sends a single character anywhere.
Password Strength Checker scores any password against real-world attack models — dictionary attacks, keyboard walks (`qwerty`, `asdfgh`), date patterns, common substitutions (`@` for `a`), and the top ~30k leaked passwords — using the open-source zxcvbn algorithm from Dropbox, running fully in your browser. Type or paste a candidate password and you get a **0–4 strength score**, an estimated **crack time** at 10k guesses/second (online throttled) and 10B/second (offline GPU), a plain-English **warning** (e.g. "This is similar to a commonly used password"), and **specific suggestions** ("Add another word or two", "Avoid dates associated with you"). It is built for the honest audit moment: checking whether your bank password really is safer than `correct-horse-battery-staple`, showing a non-technical family member why `Fluffy2019!` gets cracked in under a second, or validating a policy-mandated 12-character password before you commit it to LastPass. Nothing you type is transmitted — open DevTools → Network and confirm zero requests fire while you type. Pair with the Password Generator to build a passphrase that scores 4/4, and the Secure Note Encryptor when you need to share it. Runs entirely in your browser — no upload, no signup, no logs.
Common Use Cases
- Audit a password you've been reusing before rolling it over to a vault
- Show a teammate why "CompanyName2024!" fails a real attack model despite passing policy
- Sanity-check a new master password before locking it into 1Password / Bitwarden
- Compare passphrase strength (`purple-otter-plaza-9`) vs symbol-mangled (`P@ssw0rd!`)
- Teach kids or elderly parents password hygiene using a live score they can watch
Related tools in Security Tools
- Hash GeneratorGenerate MD5, SHA1, SHA256 and SHA512 hashes
- Passphrase GeneratorGenerate memorable passphrases from word lists
- HMAC GeneratorGenerate HMAC message authentication codes
- Bcrypt Hash GeneratorGenerate and verify bcrypt password hashes
See all Security Tools.
Frequently asked questions
How to use Password Strength Checker?
1) Open the tool. 2) Enter or upload your input. 3) Get your result instantly. Everything happens locally — nothing is uploaded.
When should I use Password Strength Checker?
Use it before saving a new password to your vault, when auditing an old one you've been reusing for years, or when explaining to a teammate why "Summer2024!" is a 3-second crack even though it "meets policy".
Is Password Strength Checker safe?
Yes. Password Strength Checker runs 100% in your browser. Inputs are never uploaded, stored, or logged — safe for confidential content.
Will quality be affected by Password Strength Checker?
Password Strength Checker performs lossless operations — your content is not re-encoded or downgraded.
What formats does Password Strength Checker support?
Password Strength Checker supports all common formats — paste, type, or load from a file.
Is Password Strength Checker free?
Yes — Password Strength Checker is completely free, with no registration, no watermarks, and no usage limits.
Is my password actually private?
Yes. Scoring runs in JavaScript in your browser using zxcvbn — no fetch, no analytics, no autofill. Open DevTools → Network before typing and you will see zero outbound requests. You can also disconnect from the internet and it still works.
What does "crack time" actually mean?
It's an estimate of how long a specific attacker model would take at that guess rate. "Online throttled" = 10 guesses/sec (a login page with rate limiting). "Offline slow hash" = 10k/sec (bcrypt). "Offline fast hash" = 10B/sec (unsalted SHA-1 on modern GPUs). If any number is under a year, treat the password as broken.
Why does a 16-character password score lower than a 4-word passphrase?
Length isn't entropy. `Aaaaaaaaaaaaaaaa` is 16 chars but ~4 bits of entropy. `correct-horse-battery-staple` is 28 chars and ~44 bits — hundreds of trillions of times stronger. zxcvbn measures guessability, not length.