Secure Password Generator

Generate cryptographically secure passwords free online using the Web Crypto API. True random generation, not predictable Math.random, with customizable length and character sets.

Length: 16

Uppercase Lowercase Numbers Symbols Exclude ambiguous (0,O,l,1)

Uses crypto.getRandomValues() -- cryptographically secure, never sent anywhere.

How to Use This Tool

Set your desired lengthSlide to choose password length, 16+ recommended

Choose character typesToggle uppercase, lowercase, numbers, and symbols

Copy and useClick the copy button -- nothing is logged or stored

Secure Password Generator is a free online tool that works entirely in your browser — no signup, no data uploaded, no limits.

Math.random() Was Never Built for Security

Most quick password generators found online use JavaScript's Math.random(), a function designed for things like animations and games where predictability does not matter. The Web Crypto API's crypto.getRandomValues() exists specifically because security-sensitive randomness needs a different guarantee -- output that cannot be predicted even by someone who understands the generation algorithm.

This generator uses crypto.getRandomValues() exclusively, the same API browsers use internally for things like generating session tokens, making the output suitable for real account passwords rather than just casual use.

Why Character Set Variety Matters Less Than Length

Adding symbols to a password increases the character set size, which increases entropy per character, but length multiplies that entropy exponentially. A 20-character password using only lowercase letters has more total entropy than a 10-character password using all four character types. Both matter, but length has the larger effect for any reasonably long password.

The Ambiguous Character Tradeoff

Characters like 0/O and l/1 look nearly identical in many fonts. If you are typing the password by hand from a printed note or reading it aloud, excluding them prevents frustrating typos. If you exclusively copy-paste from a password manager, there is no real reason to exclude them -- keeping them in slightly increases the character set and therefore the security margin.

Frequently Asked Questions

It uses crypto.getRandomValues(), the Web Crypto API's random number generator, which draws from the operating system's cryptographically secure random source. Regular JavaScript Math.random() is not designed for security purposes and can theoretically be predicted under certain conditions -- crypto.getRandomValues() is the standard actually recommended for anything security-sensitive.

If an attacker could predict or narrow down the random number generator's output, they could narrow down which passwords your generator was likely to produce, defeating the purpose of random generation. Cryptographically secure generators are specifically designed to resist this kind of analysis.

If you'll need to type the password manually (rather than copy-paste), excluding visually similar characters prevents typos. If you're using a password manager and never typing it by hand, there's no downside to including them -- it slightly increases the character set and therefore the entropy.

16 characters is a reasonable modern minimum for important accounts. For maximum security with no real downside (since you're not memorizing it), 20-24 characters with a full mixed character set provides a very large security margin against any realistic attack.

No. Generation happens entirely in your browser. Nothing is transmitted or stored -- closing the tab means the password exists only wherever you've copied it to.