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DevToolBench

Password Generator

Random passwords and passphrases, with honest entropy.

The password is drawn in this tab by your browser’s cryptographic generator. It is never sent anywhere, never stored, and cannot be recovered once you close the page — copy it into your password manager before you leave.

4–128

Everything runs in your browser. Nothing you type is sent to a server.

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Length is the setting that matters

This password generator draws each character from your browser's cryptographic random source, and the only knob that really changes the answer is the length. Every character added to a 94-character alphabet multiplies the search space by 94, which is a little more than six and a half bits. Turning on symbols for a password that stays at eight characters buys about seven bits in total; adding four characters instead buys twenty-six.

This is why the familiar advice — one capital, one number, one symbol — aged so badly. It was written for an era of eight-character limits, it pushed everyone towards the same predictable substitutions, and it produced P@ssw0rd1 in vast numbers. NIST dropped the composition rules from its guidance years ago and told sites to accept long passwords instead. If you have to choose one setting here, choose length.

Passphrases, and the arithmetic behind them

The word mode strings together entries from a fixed list of ordinary English words. Each word contributes the base-two logarithm of the list size, so a 335-word list gives a little over eight bits per word. Five words is around 41 bits; add the optional two-digit suffix and you gain another 6.6.

That is less than people assume, and it is worth being blunt about it: a passphrase is not automatically stronger than a random string, it is easier to type. Where it earns its place is on devices with no keyboard worth the name — a smart television, a console, a router's setup screen — and as the master password of a manager, which is the one secret you must remember rather than store.

The words are separated by a character you choose, and the separator is not a security feature. Neither is capitalising the first letter. Both exist because some sites still refuse a password that lacks an uppercase letter, and refusing to bend to that means not being able to sign up.

What the strength label is not

The label and the guessing time on this page describe the recipe you selected, not the string that came out of it. A generator cannot tell you that the random draw happened to produce something a dictionary attack would find, because with a uniform draw from a large alphabet that outcome is vanishingly unlikely — and if it did happen, the next draw is exactly as likely to be "bad". Reroll if a password is awkward to type. Do not reroll because it looks weak.

What the figure genuinely depends on is the defender, not you. The same password takes seconds against an unsalted MD5 dump and centuries against Argon2. You have no control over that choice, so the sensible move is to assume the worst and buy margin with length.

Then put it somewhere you will not lose it

A generated password you retype from memory is a password you will reuse, and reuse is the failure that actually empties accounts. Use a manager — the one in your browser counts — and let it hold a different secret for every site. Reserve your own memory for the master password and for the handful of credentials you type on devices a manager cannot reach.

Two habits finish the job. Turn on two-factor authentication wherever it is offered, because it survives a leaked password. And change a password only when there is a reason to, since forced rotation is the other rule modern guidance dropped: it pushes people towards small predictable edits.

Need a random identifier rather than a secret? The UUID generator produces v4 and v7 identifiers. To fingerprint a file or a string, use the hash generator, and for filler text there is the lorem ipsum generator.

Frequently asked questions

Is the password sent anywhere, or saved for later?

Neither. It is drawn by crypto.getRandomValues inside the tab you are looking at, rendered into the page, and forgotten the moment you navigate away. There is no request to a server, no history and no recovery link, which is also why you should paste it into a manager before closing the tab. A generator that could show you an old password would be a generator you should not use.

What does the entropy figure actually measure?

The size of the recipe, not the luck of the draw. Twenty characters chosen uniformly from an alphabet of 94 gives about 131 bits because there are 94 to the power of 20 possible outcomes. The specific string you got is no stronger or weaker than any other from the same recipe, which is why a generated password full of vowels is not a mistake worth clicking away from.

Why does the guessing time look so pessimistic?

It assumes the worst realistic case — an attacker with your password file, a modern GPU, and a site that hashed with something fast like a single round of SHA-256. Ten billion attempts a second is the right order of magnitude there. Against bcrypt or Argon2 with sensible parameters the same attacker manages thousands per second, so the real figure is millions of times larger. Planning for the fast hash is the honest choice, because you rarely get to know which one a site used.

Should I pick a passphrase or a string of random characters?

Pick whatever you will actually have to type. A passphrase of five words from this list carries roughly 41 bits, and six words about 50, so it needs more words than people expect to match a short random string. Its advantage is that a human can read it off a screen and type it into a television or a games console without three attempts. For anything living permanently in a manager, random characters are shorter and stronger.

Can I use one strong password everywhere?

No, and this is the single most important thing on the page. Breaches are constant and credential stuffing is automated, so a password shared between two sites is only as safe as the worse of the two. The entropy of the password is irrelevant once a site stores it badly and someone publishes the list. One unique secret per site, held in a manager, is the whole of the advice.

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