Password Generator
Create strong random passwords or memorable passphrases. Choose the length and character types, exclude confusing characters, and see the strength in bits of entropy. Everything happens in your browser.
- Cryptographically secure randomness
- Passphrase mode
- Up to 50 at once
Settings
Generator options
Your password
Entropy measures how many equally likely results the generator could produce with these settings. Meter is full at 128 bits.
Generated in your browser with crypto.getRandomValues. Nothing is sent to a server or stored.
How to use
How to Generate a Strong Password
- 1
Pick a mode
Choose Password for random characters or Passphrase for random words.
- 2
Set the options
Drag the length slider (4–128), toggle character types, and optionally exclude look-alike characters or any characters a site does not accept.
- 3
Check the strength
The meter shows the estimated entropy for your settings. Aim for at least 60 bits, and 80+ bits for important accounts.
- 4
Copy and store it
Copy one result, or generate up to 50 and copy them all. Save passwords in a password manager rather than in plain text.
Under the hood
How the Generator Works
Each character is picked with crypto.getRandomValues, the browser's cryptographically secure random number generator. To turn a random 32-bit number into an index, the tool uses rejection sampling: values that would make some characters slightly more likely than others (the "modulo bias") are thrown away and redrawn, so every character in the pool is equally likely.
When several character types are selected, the generator first places one character from each type, fills the remaining positions from the combined pool, and then shuffles the result with an unbiased Fisher–Yates shuffle. That guarantees every selected type appears at least once.
Entropy formula
bits = length × log2(pool size)
The meter refines this by subtracting the combinations that would miss a required type (inclusion–exclusion). For passphrases: bits = words × log2(wordlist size), plus log2(10 × words) when a number is added.
Worked examples
Strength at a Glance
| Settings | Pool | Approx. entropy |
|---|---|---|
| 8 chars, lowercase only | 26 | 37.6 bits (weak) |
| 12 chars, letters + digits | 62 | ≈ 71 bits (strong) |
| 16 chars, all four types | 90 | ≈ 103.6 bits (very strong) |
| 5-word passphrase | 460 words | ≈ 44 bits (fair) |
| 7-word passphrase + number | 460 words | ≈ 68 bits (strong) |
Entropy describes randomly generated secrets only. A password you invent yourself, like "Summer2024!", has far less real entropy than its length suggests.
Use cases
When to Use It
New online accounts
Create a unique password for each site and save it in your password manager.
Master passwords
Use passphrase mode with 6+ words for something strong you can still remember.
Wi-Fi and devices
Exclude similar characters so the password is easy to type on a TV or phone.
Test data and API secrets
Generate up to 50 random strings at once for seeding test accounts or config.
FAQ
Frequently Asked Questions
Is this password generator safe to use?
Yes. Passwords are created in your browser with the Web Crypto API (crypto.getRandomValues). The page does not send, log or store the passwords it generates. For extra caution you can disconnect from the internet after the page loads and it will keep working.
How long should my password be?
For accounts protected by a password manager, 16 or more random characters from all four character types is a strong default (around 100 bits of entropy). Use longer passwords for master passwords or encryption keys, and never reuse a password across sites.
What does entropy in bits mean?
Entropy is log2 of the number of equally likely passwords the generator could produce with your settings. Each extra bit doubles the number of guesses an attacker needs in the worst case, so 60 bits is about a million times harder to brute-force than 40 bits.
What is the difference between a password and a passphrase?
A password is a string of random characters. A passphrase is a sequence of random words, such as Maple-Otter-Lantern-Quiet7. Passphrases are easier to remember and type, and with enough words they are just as hard to guess. Five words from this tool's list give about 44 bits; add more words for higher strength.
Why exclude similar characters like l, 1, O and 0?
Characters such as i, l, 1, L, o, 0 and O look alike in many fonts, which causes mistakes when a password has to be read aloud or typed from paper. Excluding them makes the pool slightly smaller, which the strength meter accounts for.
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