Why a passphrase instead of a random password?

Word-based passphrases reach high entropy while staying memorable, so you don't have to write them down. NIST endorses long passphrases.

Is anything sent to a server?

No. The wordlist is bundled with the page and generation happens entirely in your browser, offline.

How strong is a six-word passphrase exactly?

The list holds 7,776 words - six to the fifth power, one entry per roll of five dice - so each word contributes about 12.9 bits. Six words is roughly 77 bits of entropy and twelve words about 155. For comparison, 77 bits is far beyond what any offline brute-force attack reaches today, which is why six is the default.

Does it weaken the passphrase if an attacker knows I used Diceware?

No, and that assumption is built into the strength figure above. The entropy is calculated as though the attacker already knows the exact wordlist and the number of words, and is simply guessing which combination came up. Security rests on the randomness of the choice, never on hiding the method.

Should I add the optional separator or symbol?

Separators make a long passphrase far easier to type accurately, which is their real value. Adding a symbol helps mainly with sites that demand one; it adds only a few bits on its own. Adding one more word buys you nearly thirteen bits, so if you want a stronger passphrase, lengthen it rather than decorating it.

🎲 Diceware Passphrase Generator

Generate strong yet memorable passphrases the Diceware way — random words drawn from the 7,776-word EFF list using your browser's cryptographically secure random generator. Choose the number of words, a separator, and optional capitals, numbers or symbols; Toolio shows the entropy in bits, a strength rating, and an estimated crack time. Nothing is generated on or sent to a server.

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Entropy

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Strength

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Est. crack time

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Options

Words: 6

Separator

Capitalize each word Add a random number Add a random symbol

Diceware picks words at random from the 7,776-word EFF wordlist using your browser's cryptographically secure random generator. A 6-word passphrase has ~77 bits of entropy — easy to remember, extremely hard to crack. Nothing is generated on or sent to a server.

Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

Diceware, popularised by the EFF, builds passphrases from common words so they're easy to remember but hard to guess. Each word from the 7,776-word list adds about 12.9 bits of entropy, so a six-word passphrase reaches roughly 77 bits — far beyond what brute-force attacks can crack. This generator uses crypto.getRandomValues() with rejection sampling for an unbiased, uniform pick, unlike Math.random(). The wordlist is bundled locally and selection happens entirely offline.

How to use

Set the number of words (6 is a strong default) and choose a separator.
Optionally turn on capitals, a random number, or a symbol for site rules.
Click Generate. Check the entropy, strength and crack-time estimate.
Copy your passphrase — regenerate until you get one you can picture.

FAQ

Why a passphrase instead of a random password?: Word-based passphrases reach high entropy while staying memorable, so you don't have to write them down. NIST endorses long passphrases.
Is the randomness secure?: Yes. It uses the Web Crypto API (crypto.getRandomValues) with rejection sampling for an unbiased choice — not the weaker Math.random().
Is anything sent to a server?: No. The wordlist is bundled with the page and generation happens entirely in your browser, offline.
How strong is a six-word passphrase exactly?: The list holds 7,776 words - six to the fifth power, one entry per roll of five dice - so each word contributes about 12.9 bits. Six words is roughly 77 bits of entropy and twelve words about 155. For comparison, 77 bits is far beyond what any offline brute-force attack reaches today, which is why six is the default.
Does it weaken the passphrase if an attacker knows I used Diceware?: No, and that assumption is built into the strength figure above. The entropy is calculated as though the attacker already knows the exact wordlist and the number of words, and is simply guessing which combination came up. Security rests on the randomness of the choice, never on hiding the method.
Should I add the optional separator or symbol?: Separators make a long passphrase far easier to type accurately, which is their real value. Adding a symbol helps mainly with sites that demand one; it adds only a few bits on its own. Adding one more word buys you nearly thirteen bits, so if you want a stronger passphrase, lengthen it rather than decorating it.