Password Generator Pro
Generate strong, random passwords with configurable length and character sets. Shows entropy in bits. Uses crypto.getRandomValues — nothing is uploaded.
Pure browser JavaScript (crypto.getRandomValues) — no external libraries.
How to use this tool
- Set the length and character sets.
- Click Generate for a cryptographically random password.
- Click Copy to copy it to your clipboard.
Generate strong, random passwords with configurable length and character sets. Shows entropy in bits. Uses crypto.getRandomValues — nothing is uploaded.
How it works
Password Generator Pro creates cryptographically random passwords using crypto.getRandomValues, the browser's secure random number generator. This is the same randomness source used by professional security software, meaning the passwords are suitable for real accounts and are not predictable.
You control the password length and which character sets to include: uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), and symbols (!@#$% etc.). The tool calculates and displays the entropy in bits, giving you a measurable indication of strength. A password with 80+ bits of entropy is considered very strong against online attacks; 128+ bits is appropriate for high-value accounts.
Every click of the Generate button produces a new password. Nothing is transmitted to a server, and the tool has no memory of previously generated passwords. Generate directly in the browser and copy with one click.
Worked example
Generate a strong password for a new account
- Set length to 20 characters.
- Enable all four character sets: uppercase, lowercase, digits, symbols.
- Click 'Generate' and note the entropy display (should be above 120 bits).
- Click 'Copy' to copy the password.
- Paste it into your password manager before using it for the account.
A 20-character random password with high entropy, stored in your password manager.
Common mistakes to avoid
- Generating a strong password and then storing it in a plain text file or browser note instead of a password manager.
- Reducing the length below 12 characters to make the password easier to type — use a password manager to type it for you and keep the length high.
- Reusing a generated password across multiple accounts — even a strong password becomes a liability if one site is breached.
Key terms
- Entropy (bits)
- A measure of password unpredictability. Each bit of entropy doubles the number of guesses required. 128 bits means an attacker would need 2^128 guesses on average.
- crypto.getRandomValues
- A browser API that generates cryptographically secure random numbers, suitable for security-sensitive applications like password generation.
Frequently asked questions
- How is randomness generated?
- Using crypto.getRandomValues — the same CSPRNG used by password managers and browsers for TLS.
- What is entropy?
- Entropy in bits measures how hard the password is to brute-force. Aim for 80+ bits for strong security.