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Password Generator

Generate a strong random password with your browser's cryptographic generator — set the length and character mix, then copy. Nothing is sent anywhere.

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Quick Answer

Pick a length (4–64) and which character sets to include — uppercase, lowercase, numbers, symbols — and the tool builds a random password using your browser's cryptographically secure generator (Web Crypto), not Math.random. A 16-character password drawing on all four sets carries roughly 103 bits of entropy. It is generated and shown only on your device; nothing is transmitted.

What the Password Generator Does

Slide the length from 4 to 64 (it opens at 16), tick the character sets you want, and a password appears — click it to copy, and press Generate for a fresh one. A small strength read-out sits underneath so you can see the effect of length and variety as you change them.

What makes the result trustworthy is the source of randomness. The tool draws from crypto.getRandomValues, the same secure generator browsers use for encryption keys. Cheaper tools lean on Math.random, whose output is predictable and unfit for secrets; this does not.

How It Works

The tool assembles a character pool from the boxes you tick — 26 uppercase, 26 lowercase, 10 digits and 26 symbols — then fills each position by drawing a random number from the Web Crypto generator and mapping it onto that pool.

The strength label (Very weak through Very strong) is a quick heuristic from the password's length and how many character classes it uses. Everything happens in the page; the password is never sent, and pressing Generate simply draws a new set of random numbers.

Generation algorithm

The randomness comes from crypto.getRandomValues, the browser's cryptographically secure generator — the same source used for encryption keys, seeded by the operating system. It is deliberately not Math.random, which is predictable and must never be used for secrets.

  1. Step 1. Build the character pool from the sets you enable (uppercase 26, lowercase 26, digits 10, symbols 26).
  2. Step 2. For each of the N positions, draw a random value from the Web Crypto generator.
  3. Step 3. Map that value onto the pool and take the character at that index.
  4. Step 4. Show the finished password plus a quick length-and-variety strength read-out.
  5. Step 5. Press Generate for a new one, or click the password to copy it.

Password entropy

bits = length × log2(pool size) (pool size = the character sets you switch on, added together)
Worked examples
16 chars, all four sets (pool 88): 16 × log2(88) ≈ 103 bits
12 chars, lowercase + digits only (pool 36): 12 × log2(36) ≈ 62 bits

Entropy here is real, not theoretical, because the tool genuinely picks every character at random. Each extra bit doubles the number of guesses an attacker needs.

Privacy

The password is generated on your device and never transmitted — generating it makes no network request at all.

Nothing is stored: refresh the page and it is gone. Copy it straight into your password manager.

Because there is no server in the loop, there is no log of what you generated anywhere.

Technical Details

Length4–64 (default 16)
Character setsUppercase, lowercase, digits, symbols (toggle each)
Symbols26 common keyboard symbols
RandomnessWeb Crypto getRandomValues (cryptographically secure)
Full pool sizeUp to 88 characters
16-char strengthAbout 103 bits with all sets on
OutputClick-to-copy, with a strength meter
Where it runsIn your browser — nothing sent

Standards & references

  • NIST SP 800-63B — the current US guidance: favour length over complexity, require at least 15 characters for a password used on its own, permit at least 64, and do not force composition rules.
  • Web Crypto — getRandomValues — the browser API for cryptographically secure random values; what this tool uses for every character.
  • Entropy (bits) — the standard measure of unpredictability — length × log2(pool) — where each bit doubles the guesses required.

Accuracy & Limitations

The strength label is a quick heuristic from length and character classes, not a full audit. A 16-character random password from this tool is genuinely strong regardless of the exact wording it shows.

Entropy figures hold only if you keep the first result. If you regenerate repeatedly until you get one that 'looks nicer', you are quietly choosing — and reducing its randomness. Take what it gives you.

A generated password is only as safe as where you keep it. Store it in a password manager; do not park it in a note, email or spreadsheet.

Mapping a 32-bit random number onto the character pool introduces a mathematically negligible modulo bias — irrelevant at these pool sizes, but worth stating plainly rather than claiming perfect uniformity.

Real-World Use Cases

New account sign-ups

Create a unique, strong password for every site so one breach can't unlock the others.

Rotating a breached password

Replace a password that turned up in a leak with a fresh random one in seconds.

Wi-Fi and device passwords

Generate a long key for a router, hotspot or device where you can paste rather than type it.

Seeding a password manager

Produce the random strings your manager stores and autofills for you.

When to use it — and when not to

Good for

  • A unique password for each website or app
  • Maximum strength where you don't need to memorise it
  • Anything you'll store in a password manager
  • Replacing a weak or reused password

Not the best choice for

  • A password you must type from memory often
  • A numeric PIN for a phone or card
  • Testing a password you already have

Need to remember it without a manager? Use the passphrase generator. Need digits only? Use the PIN generator. Want to grade a password you already have? Use the password strength checker.

Frequently Asked Questions

Is this random enough to be safe?
Yes. It uses crypto.getRandomValues, the browser's cryptographically secure generator — the same class of randomness used to create encryption keys. The output is not predictable from previous results.
Does it use Math.random?
No, deliberately. Math.random is fast but predictable and is explicitly unsuitable for security. This tool uses the Web Crypto generator instead, which is the right tool for secrets.
How long should my password be?
Longer is the single biggest lever. NIST's guidance puts the floor at 15 characters for a standalone password; this tool defaults to 16, and going to 20 or more costs you nothing if you're storing it in a manager.
Do I need to include symbols?
Length matters more than symbols, but each class you add raises the per-character entropy, so symbols help. The catch is that some sites reject certain symbols — if yours does, add length instead.
What does the entropy number mean?
It's how unpredictable the password is, in bits, calculated as length times log2 of the pool size. A 16-character password using all four sets is about 103 bits; each extra bit doubles the work to guess it.
Is my password sent to your server?
No. It is generated entirely in your browser, and producing it makes no network request. You can even disconnect from the internet and it still works.
Do you store or log the passwords I generate?
No. There is no server involved, so nothing is recorded. Once you refresh or close the page, the password is gone.
Is it safe to let a website generate my password?
It's a fair thing to question. Because this one runs locally with no network calls, the password never leaves your machine — but if you want to be certain, load the page and then go offline before generating.
What if I need to remember the password?
For something you must memorise, a random string is the wrong format — use the passphrase generator, or better, let a password manager remember a random one for you.
Why does the meter say 'Strong' and not 'Very strong'?
The meter scores a few traits — length thresholds at 12 and 16, mixed case, a digit, a symbol — so a password can be very strong in entropy yet sit one tick below the top label. The bit count is the more precise signal.
Which characters are in the symbol set?
The symbol option adds 26 common keyboard characters — ! @ # $ % ^ and similar, plus brackets, punctuation and the less-than and greater-than signs. If a site rejects one, regenerate with symbols off and lengthen instead.
Can I generate several passwords at once?
It makes one at a time; press Generate again for another. That keeps each result front-and-centre so you copy the right one.

References

Built on crypto.getRandomValues — the browser's cryptographically secure generator, not Math.random — and the password never leaves your device.

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