Free Password Generator: Build Strong Passwords in Your Browser

By Brett Bender · USA

Most password advice is easy to agree with and hard to follow. People know that a short password with a capital letter and an exclamation mark is weak, yet the same pattern keeps showing up in breach dumps because a human chose it. A free password generator removes the human from the choice. The one on this site runs in your browser: set a length between 4 and 128 characters, switch the character sets on or off, then copy the result. Nothing is uploaded. The string is built on your device and stays there.

What this password generator does

The tool gives you four controls and one output.

The length slider sets the exact number of characters, from 4 up to 128. Twelve is the default because it fits the rules most sites accept and already sits in a comfortable range for entropy. The label next to the slider follows your drag, so you always see the length you are about to generate.

Four switches decide the character pool. Uppercase adds A-Z, lowercase adds a-z, numbers add 0-9, and symbols add a set of 26 punctuation marks. With all four on, the generator draws from 88 characters. Turn the sets off that a stubborn signup form refuses, and the output stays inside the rules the form will accept.

Two more switches handle readability. Exclude similar removes the characters that look alike on screen and in print: i, l, 1, L, o, 0, and O. Exclude ambiguous removes the punctuation that some systems escape, trim, or reject, including brackets, quotes, backticks, and angle brackets. Neither switch weakens the password much, and both reduce the odds that you mistype a password you have to enter by hand.

Press Generate and the result appears in a read-only field with a copy button next to it. Below the field, a strength meter scores the password from 0 to 100, labels it from very weak to strong, and prints the changes it wants. A repeated run of characters costs points. So does a common sequence such as 123, abc, or qwe, and so does any string containing a well-worn password word.

Entropy: the number behind the word "strong"

Password strength has one honest measure: entropy, counted in bits. For a password drawn at random from a known pool, entropy is the length multiplied by the base-2 logarithm of the pool size. A dozen characters from an 88-character pool work out to 77.5 bits. Every extra bit doubles the number of candidates an attacker has to try.

Pool size grows fast when you add character types, but it grows in a straight line. Lowercase gives 26 options per position. Uppercase doubles that to 52. Digits push it to 62. The 26 symbols in this generator bring the total to 88. Length, by contrast, multiplies the whole search space: two more characters on a 12-character password multiply the work by 88 times 88, which is 7,744.

This is why a random 16-character password from the full pool, at roughly 103 bits, is stronger than a 12-character one with every symbol the keyboard offers. It is also why entropy on its own is not the whole story. A password with 77 bits of pure randomness is strong until the service it protects leaks it. Uniqueness is a separate property, and reuse is the failure mode that catches people who have otherwise done everything right.

Length first, complexity second

The composition rules that ruled the 2000s, one uppercase letter, one digit, one symbol, produced passwords like Summer2026! that look compliant and crack in seconds. NIST's digital identity guideline, SP 800-63B, responded by telling verifiers to drop composition rules, accept all printable ASCII characters plus the space, allow at least 64 characters, stop forcing periodic rotation, and screen new passwords against breach lists instead. The guideline's floor is 8 characters, and later revisions push the recommended minimum for password-only logins to 15.

In practice that means: pick the longest password the service accepts, spend your effort on length rather than hunting for the perfect mix of symbols, and treat 12 characters from the full pool as a working floor rather than a target. Sixteen is better. Twenty is better still, and the generator goes to 128 for secrets a script will paste into a config file.

Two assumptions sit behind that table. The attack is offline against a fast hash, running at 100 billion guesses per second, which is what a well-funded cracking rig does against a leaked database with weak hashing. And the figures are for exhausting the entire search space; the average attack succeeds halfway through. Rate-limited online attacks are thousands of times slower, which is exactly why a long password survives a carelessly hashed breach and a short one does not.

How to use the free password generator

1. Set the length. Check the service's maximum before you drag the slider. Banks and government portals often cap at 20 or 32 characters, while a database field or an API token can take far more.
2. Choose the character sets. Leave all four on when the form allows it. If symbols are rejected, switch them off rather than trimming characters out by hand, and turn on exclude ambiguous if the form mangles brackets and quotes.
3. Decide on the exclusion switches. Turn on exclude similar when you have to read the password aloud, write it on paper, or type it on a phone. The loss in entropy is a few bits, and the gain in accuracy is real.
4. Generate and read the meter. A 12-character result from the full pool scores in the strong band. If the meter asks for more length, raise the slider instead of toggling sets back on and off.
5. Copy the password straight into the account or the password manager before you generate another one. The field is the only place the password exists, so a refresh loses it.

Passphrases versus random strings

A passphrase is several random words strung together. The EFF long word list has 7,776 entries, which is 12.9 bits of entropy per word. Four words land near 52 bits, six words near 77.5 bits, and seven words near 90.

That comparison matters because a 52-bit passphrase is weaker than a 12-character random string, yet far easier to remember. Use the passphrase where a human has to type the secret: the master password for your password manager, the login for a work laptop, the code for a home router. Use the random string where the manager fills it in and nobody types it: the dozens of accounts you sign into a few times a year.

Mixing the two approaches usually produces the worst of both. A sentence with the first letters capitalised and a number on the end reads like a passphrase but carries the entropy of a sentence, which is to say, very little. Random words or random characters, not a remembered phrase with decoration.

Mistakes that undo a strong password

Reuse is the big one. Credential stuffing works because one breached database feeds login attempts against every other service, and a 100-bit password that appears in a dump is worth exactly as much as a 4-digit PIN. Surveys keep finding that most people reuse a password on more than one site, and public breach collections now hold billions of leaked credentials. Generate a separate password for every account and the same string stays useful for years.

A few other habits quietly cancel out good generation. Adding a digit to last year's password creates no new entropy; the cracking tools guess that transformation first. Emailing a password to yourself, or sending it in a chat, leaves it in a place you cannot delete. Storing it in an unencrypted note on a shared device is the same as posting it. And skipping two-factor authentication leaves the account protected by one secret, no matter how long that secret is. Where a service offers passkeys, that is a second improvement worth taking.

Where generated passwords fit into your setup

The workflow that holds up: a password manager stores the passwords, the generator creates them, and your memory is spent on one master secret. Every account gets its own string. Two-factor authentication goes on wherever it is offered. Passwords get changed when a service reports a breach, not on a calendar, because rotation without a compromise just makes people choose weaker variants they can remember.

The exclusion switches exist for the messy middle of that workflow, where a form rejects symbols, a legacy system caps length, or a password has to be typed into a console with no clipboard. Generate the strongest password the system will actually accept, and keep it unique. That is the whole method.

Start with the account that matters most

The easiest way to use this page: pick the account you care about losing, the one with your email, your money, or your work in it, and replace its password today. Set 16 characters from the full pool, copy the result, turn on two-factor authentication, and save the password in a manager. Then work through the rest of your logins the next time you sign into them. The generator is free, it runs in your browser, and the passwords it produces cost an attacker far more than they cost you.

Brett Bender

USA · SO reputation 19889 · Badges: 2🥇41🥈46🥉 · SO member since 2009