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UFOZoo

Password Generator: Strong Random Passwords 12-64 Chars

Password generator online: create strong random passwords from 12 to 64 characters with custom character sets and Web Crypto randomness.

Updated 2026-08-16

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Features

  • Cryptographically secure generation using the browser's Web Crypto API (CSPRNG)
  • Real-time strength analysis with entropy calculation and estimated crack time based on modern GPU capabilities
  • Customizable character sets: choose uppercase, lowercase, numbers, and symbols to meet specific site requirements
  • Exclude similar characters option to avoid confusion between O/0, I/l/1 when manually typing passwords
  • Memorable passphrase mode using random word combinations, perfect for master passwords you need to memorize
  • Password history saves last 10 generated passwords in browser session storage for quick access
  • Flexible length control from 8 to 64 characters with quick presets for common lengths
  • In-browser generation via Web Crypto API: passwords are produced locally without network requests

How to Use

  1. 1Select your desired password length using the slider (recommended: 16+ characters for maximum security)
  2. 2Choose which character types to include: uppercase, lowercase, numbers, and/or symbols
  3. 3Toggle 'Exclude Similar' to avoid confusing characters like O/0 and I/l/1
  4. 4Switch to 'Passphrase' mode for memorable word-based passwords
  5. 5Click 'Generate' to create a new random password instantly
  6. 6Use the copy button to copy the password to your clipboard
  7. 7View password history to access previously generated passwords
  8. 8Check the strength indicator to ensure your password meets security requirements
  9. 9How to create a password for a new account: set a length of 12-16 characters, enable all four character types, and exclude similar characters so the password is easy to type manually.
  10. 10How to build a memorable master password: switch to passphrase mode, pick 4-5 words, and enable 'add a number': the result is strong yet easy to remember.

Frequently Asked Questions

Is this password generator safe to use?

Yes, all generation runs locally in your browser using the Web Crypto API, so your passwords never leave your device.

How does the cryptographically secure generation work?

We use the browser's built-in crypto.getRandomValues() API, which accesses your operating system's entropy pool, random data gathered from hardware timing, mouse movements, and other unpredictable sources.

What password length should I use?

For general accounts: 12-16 characters. For banking and sensitive accounts: 20+ characters. Each additional character exponentially increases security: a 20-character password is billions of times stronger than a 12-character one.

What is password entropy?

Entropy measures password randomness in bits. Higher entropy = harder to crack. Our tool calculates entropy based on length and character diversity. 80+ bits is strong, 100+ bits is very strong, 128+ bits is military-grade.

Can generated passwords be cracked?

Theoretically any password can be cracked given infinite time, but a 16-character random password would take centuries to crack with current technology. Our strength indicator shows estimated crack times based on modern GPU capabilities.

What are 'similar characters' and why exclude them?

Characters like O (letter) and 0 (zero), or I (uppercase i), l (lowercase L), and 1 (one) look identical in many fonts. Excluding them prevents confusion when manually typing passwords.

What's the difference between password and passphrase?

Passwords use random characters (K9#mP2$v). Passphrases use random words (correct-horse-battery). Passphrases are easier to memorize while remaining secure due to length. Both are generated cryptographically secure.

Why shouldn't I reuse passwords?

If one service is breached and your password exposed, attackers can access all your other accounts using the same password. This 'credential stuffing' attack is extremely common. Use unique passwords for every account.

How do I generate a password that meets specific website requirements?

Many websites require at least one uppercase letter, one number, and one special character. Use the character type checkboxes to enforce these requirements. Set a length of 12-16 characters for most sites. The strength indicator shows real-time feedback on your configuration before you generate.

How does the password history feature work?

The password history stores your last 10 generated passwords in browser session storage for quick access. You can review or copy previously generated passwords without reconfiguring. The history is temporary: it is cleared when you close your browser tab. This is a convenience feature, not a replacement for a dedicated password manager.

Why does a website reject a password the generator says is strong?

Websites enforce their own arbitrary rules on top of strength: a minimum or maximum length (some cap at 16), a required special character from a limited set, or bans on repeating and sequential characters. The generator measures entropy, not any single site's policy. Check the site's stated requirements and mirror them with the character checkboxes and length field: most rejections are a missing special character or a length outside the site's range. If a site caps length at 16, entropy is limited by their rule, not by the generator.