A strong password is a random string of characters that resists dictionary guesses and brute-force searches by maximizing entropy—the number of unpredictable bits encoded across its length and character set. Digital services increasingly rely on such secrets to guard accounts, encrypted volumes, and API keys. Modern compliance standards explicitly recommend random, high-entropy generators over memorable phrases.
This generator lets you choose length, character pools, and whether each symbol must be unique. A reactive engine draws from the active pool, builds a string on the fly, then evaluates its strength with an open-source estimator. In parallel, it calculates theoretical entropy and an approximate crack time based on ten-billion guesses per second.
Use it before creating a new email, cloud, or banking login: generate, copy, and save the result in your password manager, or download it as a text file for offline transfer. Avoid reusing passwords or writing them on paper where others may see them; losing the string means losing access.
Random password generation relies on combinatorial explosion. If a character set contains N distinct symbols and a password is L characters long, the total search space equals NL. Entropy, drawn from information theory, transforms that space into bits: E = L × log2N. Each added bit doubles attacker effort, so higher E exponentially slows brute-force attacks and meets recommendations in NIST SP 800-63B. The tool shows entropy live, warns when patterns reduce randomness, and updates its meter instantly to guide safe choices.
Where L is password length and N is the active character-pool size.
| Score | Label | Guidance |
|---|---|---|
| 0 | Very Weak | Avoid for any purpose. |
| 1 | Weak | Improper for long-term accounts. |
| 2 | Fair | Acceptable only for low-risk throw-aways. |
| 3 | Good | Suitable for personal accounts with MFA. |
| 4 | Strong | Preferred for critical or privileged access. |
Example (L = 12, N = 62):
≈ 71.6 bits entropy → estimated crack time > 37 000 years at 1010 guesses / s.
References: NIST SP 800-63B; Shannon (1948) “A Mathematical Theory of Communication”; Mazurek et al. (2013) “Measuring Password Guessability”; Shay et al. (2016) “Assessing Strength Meters”.
All computations occur in your browser; no input or output is transmitted, supporting GDPR and comparable regulations.
Follow these actions to build and keep a resilient secret:
No. Everything happens locally; nothing leaves your device.
The estimate divides the total search space by a fixed rate of 10 billion guesses per second and converts seconds to human-readable units.
Excluding look-alike characters reduces mistyping and visual confusion, especially when reading aloud.
Reusing passwords across services undermines security; generate a fresh one for every account.
The list keeps the 20 most recent passwords for quick recall; older ones drop off automatically.