Generated locally, never transmitted

Passwords built like a vault door

Every character comes from your browser's cryptographic random number generator — not a server, not a log file. Set your terms, forge a password, and see exactly how hard it would be to break.

forging…

Length16

Uppercase A–Z Lowercase a–z Numbers 0–9 Symbols !@#$ Exclude look-alikes 0 O 1 l I

Strength gauge

Strong

0 bits of entropy

Offline attack (est.): —
Online attack (est.): —
Character pool: —

The mechanics

How password strength is actually measured

Strength isn't a feeling — it's a count. Every character you add multiplies the number of possible passwords, and that count is what an attacker actually has to search.

Keystone measures strength in bits of entropy, the same unit cryptographers use. For a random password, entropy is:

bits = length × log₂(pool size)

A pool of 26 lowercase letters gives about 4.7 bits per character. Add uppercase, digits, and symbols and the pool climbs past 90 characters — worth roughly 6.55 bits each. Length is still the biggest lever: two extra characters usually beat one extra character set.

Length	lowercase only	letters + digits	full symbol set
8	38 bits	48 bits	52 bits
10	47 bits	60 bits	66 bits
12	56 bits	71 bits	79 bits
14	66 bits	83 bits	92 bits
16	75 bits	95 bits	105 bits
20	94 bits	119 bits	131 bits

Theoretical maximum, assuming a fully random draw from the stated pool on every character. Most security guidance treats 60+ bits as strong for an offline-crackable hash.

Field notes

Habits that quietly weaken a password

These don't look risky in the moment — they're what actually shows up in breach data.

Predictable substitutions

Swapping "a" for "@" or "e" for "3" barely changes the search space — cracking tools have tried these substitutions for decades.

Dates and sequences

Birth years, "123", and keyboard walks like "qwerty" collapse a huge pool down to a few thousand likely guesses.

Reusing one password everywhere

A single breached site can expose the same password for every other account it's used on. Unique passwords contain the damage to one place.

Padding instead of randomizing

Adding "!!!" to a memorable word adds far fewer bits than four genuinely random characters would.

Short "strong-looking" passwords

Mixed case and symbols help, but an 8-character password is still short. Length outperforms complexity almost every time.

Storing passwords in plain text

A strong password saved in an unencrypted note or spreadsheet is only as safe as that file. A password manager's vault is encrypted at rest.

Questions

Frequently asked

Does Keystone store or transmit anything I generate?

No. Every password is generated inside your browser using the Web Crypto API (crypto.getRandomValues). Nothing is sent to a server, logged, or saved — closing or refreshing the tab clears it completely.

What makes this different from a plain random-string generator?

The randomness itself is cryptographically secure rather than pulled from Math.random(), which isn't designed to resist prediction. Keystone also shows the actual entropy and crack-time math behind each password instead of a vague "strong" label.

Password or passphrase — which should I use?

Both are strong when they're long enough. A character password packs more entropy per keystroke, which suits places that enforce short maximum lengths. A passphrase trades some entropy for something a human can actually read aloud or type on a phone keyboard — useful for a device passcode or a password manager's own master password.

How is the crack-time estimate calculated?

Keystone takes the password's entropy in bits, halves the full search space to approximate an average-case guess, and divides by an assumed guessing rate — 10 billion guesses/second offline for a fast attacker with the hash algorithm and hardware to match, or 100 guesses/second online against a service with basic rate-limiting. Real attacks vary; treat the numbers as an order of magnitude, not a guarantee.

Should I still use a password manager?

Yes — a generator solves randomness, but a manager solves storage and reuse. Generate here, save into an encrypted vault, and let the manager autofill it so you never have to remember or retype it.