Passphrase Generator
Passphrase generator — create strong, memorable multi-word passphrases using your browser’s cryptographic random generator. Choose word count, separators, capitalisation, numbers and symbols, and see the live entropy and estimated crack time. Nothing is generated on or sent to a server.
Passphrase Generator
Generated with your browser’s cryptographic random generator from a built-in list of — words. Nothing is sent anywhere.
How to Use the Passphrase Generator
Choose the length
Drag the slider to set how many words you want.
Tune the style
Pick a separator and toggle capitals, a number or a symbol.
Check the strength
Watch the entropy, rating and crack-time update live.
Copy and store
Copy it and save it in your password manager.
Why Words Beat Symbols
For years we were told a strong password meant a short jumble of letters, numbers and symbols — something like “P@ssw0rd!”. The trouble is that such passwords are hard for humans to remember and, it turns out, not especially hard for computers to guess. The modern advice, popularised by the “correct horse battery staple” comic and now backed by security agencies, is to use a passphrase: several randomly chosen words strung together. It is long enough to resist brute force yet memorable enough to type, and that combination is what makes it genuinely useful. This generator builds exactly that, and shows you the maths behind it as you go.
The strength of any secret comes down to entropy — the number of equally likely possibilities it could have been, expressed in bits. Each additional bit doubles the work an attacker must do, and the cleanest way to add bits is to add randomly chosen words: every word multiplies the search space by the size of the word list. That is why a four-to-six word passphrase typically dwarfs a fiddly eight-character password in real strength. The tool reports the live entropy in bits, a plain-language rating from very weak to very strong, and a deliberately conservative crack-time estimate that assumes a well-resourced offline attacker trying about a hundred billion guesses a second. Optional capitals, a number and a symbol add a little more entropy and help satisfy sites with rigid rules, but the slider for word count is the lever that really matters.
Just as important as the strength is how the randomness is produced. This tool uses the Web Crypto API — the browser’s cryptographically secure random number generator — with rejection sampling so that every word is equally likely and no statistical bias creeps in. It never uses Math.random, which is fast but predictable and unfit for secrets. The word list is bundled into the page and served from our own domain, in keeping with the principle that nothing security-relevant should depend on a third-party CDN. Crucially, the entire process happens on your device: the words are chosen, the passphrase is assembled, and its strength is scored entirely in your browser. Nothing is transmitted, logged or stored, so you can even go offline before generating. Pair the result with a password manager so every account gets its own unique secret, and reserve memorised passphrases for the few places that truly need them.
Add a word, not a symbol: each random word multiplies the possibilities, while a lone symbol barely moves the needle.
10 Facts About Passphrases
A passphrase of random words can beat a short complex password for strength and memorability.
Strength comes from entropy — the size of the search space.
Each extra random word multiplies the possibilities.
This tool uses the browser’s cryptographic RNG, not Math.random.
The famous “correct horse battery staple” idea popularised word passphrases.
Length usually matters more than obscure symbols.
Reusing a password is riskier than a weakish unique one.
A password manager lets every login have a unique secret.
Entropy is measured in bits; each bit doubles the guesses.
Generation here is fully client-side — nothing is uploaded.
Frequently Asked Questions
- A passphrase is a secret made of several words, such as “maple-Harbor-7-cobalt”, rather than a single short string. Because it is long, it can be very hard to guess while remaining easy for a human to remember and type. A handful of randomly chosen words often provides more real-world strength than a short password peppered with symbols.
- It draws words at random from a built-in list using your browser’s cryptographic random number generator (the Web Crypto API), with rejection sampling so every word is equally likely and there is no bias. It deliberately does not use Math.random, which is not designed for security. The word list is bundled with the page and served from our own domain.
- Entropy, measured in bits, is the base-two logarithm of how many equally likely possibilities your passphrase could have been. Each extra bit doubles the work an attacker faces. As a rough guide, under 28 bits is very weak, around 60 bits is reasonable for most accounts, and 80 bits or more is strong. The tool shows the live figure as you change options.
- It is a deliberately conservative guide. The estimate assumes an offline attacker who has stolen a password database and can try about one hundred billion guesses per second against fast hashing, and it uses the expected number of guesses (half the search space). Real attacks vary enormously, but the figure is useful for comparing options — and it errs toward assuming the attacker is strong.
- Usually, yes. Each random word adds far more entropy than swapping a letter for a symbol, and length is what defeats brute-force and guessing attacks. A four-to-six word random passphrase is both stronger and easier to remember than something like “P@ssw0rd1”. Symbols and numbers help at the margins, which is why this tool offers them as options.
- They each add a little entropy and can satisfy sites that demand a digit or symbol, so they are worth enabling. But the biggest lever by far is the number of words. Add a number or symbol to meet a site’s rules, and rely on word count for genuine strength rather than hoping a single symbol makes a short phrase secure.
- No. The entire process — choosing words, assembling the passphrase, and scoring its strength — happens in JavaScript on your device. Nothing you generate is transmitted, logged or stored anywhere. You can even disconnect from the internet after the page loads and it will keep working.
- The safest approach is a reputable password manager, which lets every account have its own unique, strong secret that you never have to memorise beyond one master passphrase. If you must remember one by heart — your device login or your manager’s master password — a word passphrase is ideal because it balances strength with recall.
- In principle any random output can repeat, but with a sufficiently long passphrase the odds are astronomically small — that is the whole point of high entropy. Using more words makes a collision effectively impossible. Each generation is independent and unpredictable because it is driven by the cryptographic RNG.
- Completely free, with no account or limit. It works offline once the page has loaded and collects no data.
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