Password & random number generator
Create passwords and random integers within a range using your browser’s secure random numbers.
Generate password
Generated passwords are never saved or uploaded. They disappear when you reload.
Generate random integers
Generated numbers are never saved or uploaded. They disappear when you reload.
Save options
Only options such as length, character types and range are saved, and only in this browser. Generated values are never saved.
How to use the password & random number generator
Passwords and numbers are created from secure random numbers produced by your browser’s crypto.getRandomValues. Generated values are shown only on this screen and are never saved or uploaded.
- Choose a length and character types, then press Generate password.
- Enter a range and a count, then press Generate numbers to draw integers within the range.
- Copy the result and paste it into a password manager or wherever you need it.
How is entropy calculated?
We count the strings of length N that contain every selected character type and show the base-2 logarithm of that count as entropy in bits. With a single character type this equals length × log2(number of characters); guaranteeing every selected type slightly reduces the count, so the value is a little lower.
This is only a theoretical estimate for an attacker who knows the length and character types and must guess at random; it does not guarantee safety. Not every combination is exactly equally likely with this method, so the real value can be slightly lower than shown. A password reused elsewhere, or exposed by a leak, phishing or malware, is not protected regardless of entropy.
The entropy of random integers is the sum of log2 of the number of choices for each draw, and it includes the order of the draws.
How are numbers drawn evenly?
Taking a random number modulo the range size makes some values appear more often, which is called modulo bias. This tool uses rejection sampling: it discards draws above the largest multiple of the range size and draws again, so every value has the same probability. Draws without repeats use the Fisher–Yates method, one value at a time.
Limits
- Password length is 8 to 128 characters.
- Random integers range from -9,007,199,254,740,991 to 9,007,199,254,740,991, the size of the range is at most 9,007,199,254,740,991, and at most 1,000 numbers are drawn at a time.
- Only the symbols !@#$%^&*()-_=+[]{}:;,.? are used, and some sites may not accept all of them.
- A passphrase mode made of words is not offered because this tool does not include a vetted word list.
- If a browser has no secure random generator, no fallback is used and an error is shown instead.
Frequently asked questions
Are generated passwords uploaded or saved?
No. They are created only inside this browser and shown only on screen. The save button stores only options such as length and character types, never generated values. They disappear when you reload, so paste them into a password manager right away if you need them.
Why exclude look-alike characters?
It removes characters such as I, l, 1, O and 0 that are hard to tell apart in some fonts, which reduces mistakes when copying by hand. With fewer characters, entropy is slightly lower.
Can I use it for an official prize draw?
Not recommended. There is no audit trail or external verification.