All tools

Passphrase generator

A long passphrase of random words is both strong and rememberable. This builds one using your device's secure random source and shows the exact entropy. It runs entirely in your browser — nothing is sent anywhere.

Number of words: 5 Each word adds exactly 12 bits of entropy (chosen from a fixed 4,096-word list). Four or five words is strong for everyday use; six or more for high-value secrets.

Separator

Extras

Capitalise each word Add a random digit Add a random symbol

Capitalising is a fixed style choice, so it adds no entropy. A random digit adds ~3.3 bits; a random symbol adds ~3.5 bits. Some sites require a digit or symbol, which is the main reason to turn these on.

Generating…

Entropy: —
Strength: —
Offline crack (avg): —

How this works, and what it can't know. Words are chosen uniformly at random with crypto.getRandomValues — your browser's cryptographically secure generator — from a fixed, public 4,096-word list, so each word contributes exactly 12 bits. The entropy shown is a true lower bound for how this passphrase was generated. The "offline crack" figure assumes an attacker who knows you used this method and tries 100 billion guesses per second; it is a rough guide, not a guarantee. Generate the passphrase, memorise it or store it safely, and don't reuse it.