Free secure password generator. Create cryptographically strong random passwords with custom length and character options.
Generate cryptographically strong, random passwords in your browser — choose the length and whether to include uppercase, lowercase, numbers, and symbols. Each password is created locally with the browser secure random source and is never sent anywhere, logged, or stored.
Strength comes from length and randomness, not from clever character substitutions a human would remember. Each additional character multiplies the number of possible combinations, so a 16-character random password is vastly harder to brute-force than an 8-character one, no matter how many symbols the short one has. A random 16-character password mixing all four character types is strong enough for any account today.
A long passphrase of random words can be both strong and memorable, but for passwords you keep in a manager, maximize length and character variety and never reuse them. Reuse is the real risk: when one site is breached, attackers replay the same email and password against every other site, an attack called credential stuffing. A unique random password per site stops it entirely.
Generate a unique password here, save it in a password manager, and turn on two-factor authentication for important accounts. To see whether an address has appeared in known breaches, use the breach checker; to measure an existing password against common attack patterns, use the password strength checker.
A secure password generator creates random, high-entropy passwords using cryptographically secure random number generators (CSPRNGs). Unlike human-chosen passwords—which tend to follow predictable patterns, use dictionary words, and reuse across services—generated passwords maximize randomness, making them resistant to brute-force attacks, dictionary attacks, and credential stuffing.
Password security is measured in bits of entropy—the amount of randomness in the password. A 12-character password using uppercase, lowercase, digits, and symbols provides approximately 79 bits of entropy, meaning an attacker would need to try an average of 2^78 combinations. For context, modern GPU-based crackers can test billions of password hashes per second against weak hashing algorithms, making password length and randomness critical defenses.
Entropy measures the unpredictability of a password. It depends on the character set size and password length:
Entropy formula: E = L × log₂(C)
| Character Set | Set Size (C) | Bits per Char | 12-char Entropy | 16-char Entropy |
|---|---|---|---|---|
| Lowercase only | 26 | 4.7 | 56.4 bits | 75.2 bits |
| Lower + upper | 52 | 5.7 | 68.4 bits | 91.2 bits |
| Lower + upper + digits | 62 | 5.95 | 71.4 bits | 95.3 bits |
| All printable ASCII | 95 | 6.57 | 78.8 bits | 105.1 bits |
Recommended minimums:
Why randomness matters: The password "P@ssw0rd123!" has 95^12 possible combinations in theory, but because it follows predictable patterns (capital first letter, common substitutions, trailing numbers and symbol), it falls in minutes to rule-based attacks. A truly random password like "k7#mQ2!vLp9&" from the same character set would take centuries.
Use cryptographically secure random number generator (CSPRNG), not Math.random(). Include: 16+ characters, uppercase, lowercase, numbers, symbols. Avoid: dictionary words, personal info, patterns. Our tool uses Web Crypto API (window.crypto.getRandomValues) for true randomness. Generate unique password per account. Store in password manager. Verify strength using entropy calculator. Longer = better (20+ chars ideal).
Cryptographically secure pseudo-random number generator (CSPRNG) produces unpredictable random values suitable for security. Uses entropy from OS (hardware noise, timing). Not guessable like Math.random(). Examples: Web Crypto API, /dev/urandom, CryptGenRandom. Essential for passwords, encryption keys, tokens. Standard random generators are predictable - never use for security. CSPRNG passes statistical randomness tests.
Random passwords (CSPRNG-generated) are strongest - maximum entropy, no patterns. Memorable passwords (passphrases) are easier to remember but slightly weaker. Best approach: random passwords in password manager (most accounts) + memorable passphrase for master password. Example passphrase: "Tiger!Climb$Forest29". Avoid: common phrases, song lyrics, quotes. Use password manager to eliminate memorization need for most accounts.
Yes, if using client-side CSPRNG (no server transmission). Our tool generates passwords in your browser - never sent to server. Check: uses crypto.getRandomValues(), open-source code, HTTPS. Avoid: generators requiring server requests, closed-source tools, non-HTTPS sites. Most secure: offline generator or password manager. Clear clipboard after copying. Never save generated passwords in browser autofill without master password.
Minimum 16 characters for strong security. Longer = exponentially stronger. Recommendations: 16 chars (good), 20 chars (better), 32 chars (excellent for high-value accounts). Master passwords: 20-30 chars (passphrases). Short passwords (<12 chars) are vulnerable to brute-force. Each added character increases cracking time exponentially. Modern systems support 64+ characters. Use maximum allowed length for critical accounts.
Yes, if allowed. Special characters (!@#$%^&*) increase entropy and character space. Some systems limit allowed symbols - check requirements. Avoid ambiguous characters (O/0, I/l/1) if typing manually. Balance: length matters more than character variety. 20 char lowercase > 10 char with all types. Best: 16+ chars with uppercase, lowercase, numbers, and symbols. Use password manager to handle complex passwords.
Do not try - use password manager instead. Password managers: store encrypted passwords (AES-256), auto-fill credentials, sync across devices, generate unique passwords. Recommended: Bitwarden, 1Password, LastPass, KeePass. Exception: master password - use memorable passphrase (20+ chars). Write master password on paper, store in safe. Enable MFA on password manager. Better to store securely than use weak memorable passwords.
Properly generated passwords (16+ chars, true random, CSPRNG) take centuries to crack with current technology. Weak points: password reuse, phishing, keyloggers, compromised password manager. Quantum computers (future) threaten current encryption - use 32+ chars for future-proofing. Defense: unique passwords per account, MFA, breach monitoring, regular security audits. No password is uncrackable - layer security with MFA.