Password Strength Checker
A free local tool that checks password length, common terms, sequences, and repetition. See a four-level basic rating and feedback as you type, without sending or saving your input. This is a heuristic, not a breach check or security guarantee.
Up to 1,024 UTF-16 code units. The character count uses Unicode code points.
This basic check uses length and a few predictable patterns. It does not perform comprehensive dictionary or breach checks, estimate cracking time, or guarantee security. Avoid entering passwords you actually use.
How to use
- Enter a candidate string. Avoid entering passwords you actually use.
- Review the basic strength rating, character count, and detected predictable patterns. Results update as you type.
- Use the eye button to reveal the input only when needed. Choose Clear to remove the input and reset the result.
About this tool
The Password Strength Checker helps you inspect whether a candidate is short or contains a few predictable features. Length determines the initial four-level rating. A small list of common terms, some character substitutions, alphabet and digit runs, keyboard sequences, and repeated strings can reduce that rating. Adding uppercase letters, digits, or punctuation alone does not automatically earn a high score.
The word list and pattern rules are limited. The tool does not understand names, birthdays, sentence meaning, or how predictable a combination of words might be. A high rating for a long string therefore does not prove that it is secure. The input lives only in React state and is not placed in a URL, browser storage, or an external API request. Spaces are preserved, and the displayed character count uses Unicode code points, including Japanese characters and emoji.
For example, Password123! contains uppercase and lowercase letters, digits, and punctuation, but receives a low rating because it includes a common term. Repeating Ab1! four times is also detected as repetition. Keep the input hidden when other people might see your screen, and clear the field when you finish.
The initial rating uses these length ranges: under 8, 8–11, 12–15, and at least 16 characters. Any detected predictable pattern limits the result to the lowest level regardless of length. Input is limited to 1,024 UTF-16 code units; some emoji consume two units toward that limit. The displayed code-point count can differ from the number of visible symbols when a symbol combines multiple code points.
Frequently asked questions
Is my input sent or saved?
The tool does not send your input to a server or record it in browser storage. Clear resets both the field and the assessment, and hides the password again.
Does Strong mean secure?
No. This basic heuristic checks length and a few patterns. It does not check breach databases or a comprehensive dictionary, estimate cracking time, or detect reuse on other services.
Why can a long string receive a weak rating?
Detected common terms, sequences, repetition, or very few distinct characters lower the score. Repeating a short block many times increases its length without earning a higher rating.