Util Tools What makes a password strong?
Two things matter most: length and randomness. A long password drawn from a large character set has vastly more possible combinations, making it harder to guess or brute-force. A truly random password also avoids the predictable patterns (names, dates, keyboard runs, common substitutions) that attackers try first. This generator builds long, random passwords and shows their strength as you tune them.
Generated with real cryptographic randomness
The quality of a random password depends on the quality of its randomness. This tool uses the browser's
Web Crypto API (crypto.getRandomValues()), a cryptographically secure source,
rather than Math.random(), which is predictable and unsafe for security. Everything happens
locally in your browser, and no password you generate is ever stored or sent anywhere.
What is password entropy?
Entropy, measured in bits, quantifies how unpredictable a password is: each extra bit doubles the number of possibilities. As a rough guide, under 50 bits is weak, 60 to 80 bits is good for most accounts, and 100+ bits is very strong. Adding length increases entropy faster than adding complexity, which is why a long passphrase can beat a short, symbol-heavy password.
Use a password manager
The safest approach is to generate a different strong password for every account and store them in a reputable password manager, so you only have to remember one master password. This eliminates reuse, which is the single biggest real-world password risk: one breached site should never compromise your others. Pair unique passwords with two-factor authentication wherever it is offered.
최종 업데이트: 2026년 9월