Words you can actually type, chosen at random
A passphrase of independently chosen words, drawn with your browser's cryptographic randomness. Easier to type and to remember than a string of symbols, and the strength is stated exactly — including how big the word list really is.
Processed locally in your browserNothing you enter here is uploaded, logged or sent to any server.
How big the word list is, and why that is the whole story
This list holds — words, which makes each independently chosen word worth — bits. Multiply by the number of words and that is the entropy — provided the words really are chosen independently, which here they are: each is drawn afresh from the whole list, so the same word can appear twice. Drawing without replacement would look tidier and would quietly change the arithmetic.
That is a smaller list than the well-known Diceware ones. The EFF's long list has 7,776 words, worth 12.9 bits each against this list's figure, so a phrase from it reaches a given strength in fewer words. The list here was written for the tool rather than taken from a published one, which keeps the licensing question from arising — and the honest way to make up the difference is simply to use more words. The generator defaults to seven for that reason.
What matters is that the number you see is the real one. A tool quoting 12.9 bits a word while shipping a list of five hundred is describing somebody else's list.
Capitalising every word adds nothing
If every word starts with a capital, an attacker knows every word starts with a capital. There is no choice being made, so no information is added, and the entropy figure here does not move when you turn it on — it is offered because some systems demand a capital letter, not because it helps.
Random capitalisation is different: a coin flip per word really is one bit per word, and the figure goes up accordingly. It also makes the phrase considerably harder to type, which for a passphrase is most of the point lost. Adding one more word is worth more and costs less.
What this tool does not claim
No tool on this site is described as unbreakable, military grade, or completely secure, because none of those phrases means anything a person could check. What is written down instead is which standard is used, which library implements it, and what the tool has been tested against.
Everything here runs in your browser using its built-in Web Crypto implementation. Nothing is uploaded, and there is no server that could receive it. That is a real and checkable property — open your browser's network tab and use the tool.
When a passphrase beats a password
Whenever you have to type it. A disk-encryption password, a device login, the master password for your password manager — these get typed on phone keyboards, on unfamiliar layouts, and while somebody is waiting. Seven random words are quick and accurate to type; sixteen random symbols are neither.
For everything a password manager fills in on your behalf, use the password generator instead. Nothing you never type needs to be memorable, and a longer random string is strictly better.
Do not tidy it up
The temptation with a generated phrase is to swap a word you dislike, or reorder them so they nearly make sense. Both remove randomness — and it is precisely the randomness being measured. If a phrase is unusable, generate another one; the tool is not running short.
The same applies to reusing a phrase you thought of yourself. A memorable phrase from a book, a lyric, or your own head is not drawn from a list of hundreds of words; it is drawn from a list of things a person might think of, which is very much shorter and which attackers have enumerated.
Related
The password generator for anything a manager will type for you, or the entropy explorer to see how word count and list size trade off against each other.
Questions people actually ask
How many words do I need?
It depends on the list, which is why the exact figure is on the page rather than a rule of thumb. Each word from this list is worth about 9.1 bits, so seven words is roughly 64 bits and nine is about 82. If you are comparing against advice written for a Diceware list of 7,776 words, those words are worth 12.9 bits each — so a six-word Diceware phrase and an eight-and-a-half-word phrase from here are about equivalent.
Why is the word list smaller than Diceware's?
Because it was written for this tool rather than taken from a published one, which keeps the licensing question from arising at all. The honest consequence is that phrases need more words to reach the same strength, and the generator defaults to seven for that reason. What matters is that the number shown is the real one — a tool quoting 12.9 bits per word while shipping five hundred words is describing somebody else's list.
Can the same word appear twice?
Yes, and it must be able to. Each word is drawn afresh from the whole list, which is what makes the entropy exactly words × bits-per-word. Preventing repeats looks tidier and quietly changes the arithmetic to something smaller than the figure being displayed.
Does capitalising the words help?
Not if you capitalise all of them — an attacker knows they are all capitalised, so no choice has been made and no information added. The figure on this page does not move when you turn that on. Random capitalisation genuinely adds one bit per word, and also makes the phrase much harder to type; one more word is worth more and costs less.
Can I swap out a word I do not like?
You can, but it costs you the thing being measured. Every substitution you make is a choice a person made, and choices people make are far more predictable than random draws. Generating another phrase is free.
Is the phrase sent anywhere?
No. It is generated in your browser from local randomness and a word list bundled with the page. Nothing is fetched and nothing is transmitted.