Password Generator

Why Do You Need a Strong Password?

In October 2025, a small accounting firm in Cleveland discovered that an attacker had accessed their client portal using a password that an employee had reused from a breached retail website. The password was "Summer2024!" It took the attacker less than 2 seconds to find it in a database of 19 billion leaked passwords. The firm lost client trust, faced regulatory fines, and spent $40,000 on incident response. All because of one reused password.

Weak and reused passwords remain one of the leading causes of account breaches. According to the 2026 Verizon Data Breach Investigations Report, ransomware appeared in 48% of all breaches, the highest figure in DBIR history. A study of 19.03 billion leaked passwords found that 94% were reused or duplicated. Stolen credentials appeared as the initial access vector in 22% of all confirmed breaches in the 2025 Verizon DBIR. Dictionary attacks, credential stuffing, and brute-force attacks can crack short, predictable passwords in seconds. A strong, randomly generated password with sufficient length and character variety can take billions of years to crack with current technology.

This generator uses your browser's built-in cryptographic random number generator (Web Crypto API) to produce passwords that are statistically unpredictable. Unlike simple random functions, crypto.getRandomValues() is designed specifically for security-sensitive operations. The NIST SP 800-63B-4, published in August 2025, is the current federal standard for digital authentication and password management.

What This Generator Does

This tool generates one or more random passwords based on your chosen character sets, length, and exclusion rules. It also shows your password's entropy, a measure of how difficult it would be to guess through brute force. For encoding and decoding data, try our Base64 Encode / Decode tool.

• Inputs: Password length (4-128), character sets (lowercase, uppercase, numbers, symbols), exclusions, and count
• Outputs: One or more random passwords, entropy estimate in bits, strength rating, and character pool size

How the Calculation Works

Password Entropy

Entropy measures the unpredictability of a password. A 12-character password using only lowercase letters (26 characters) has 12 x log2(26) = 56.5 bits of entropy. The same length using all character sets (approximately 94 characters) gives 12 x log2(94) = 78.7 bits. More bits means exponentially harder to crack. NIST SP 800-63B-4 emphasizes password length as the primary factor in password strength, noting that composition rules (requiring mixtures of character types) have less benefit than initially thought and impose significant usability costs.

Strength Thresholds

• Very Weak (below 28 bits): Crackable instantly with modern hardware
• Weak (28-36 bits): Crackable in hours or days with dedicated hardware
• Reasonable (36-60 bits): Adequate for low-risk accounts
• Strong (60-128 bits): Suitable for most accounts. Recommended minimum for sensitive services
• Very Strong (128+ bits): Essentially uncrackable with current and foreseeable computing power

NIST SP 800-63B-4 requires that passwords used as single-factor authentication be a minimum of 15 characters in length. For multi-factor authentication, the minimum is 8 characters. The standard recommends allowing passwords up to at least 64 characters and accepting all printing ASCII characters, spaces, and Unicode characters.

How to Use the Generator

1. Set your desired password length using the slider. Longer is always stronger. NIST recommends at least 15 characters for single-factor authentication
2. Select which character types to include. Using all four sets maximizes entropy per character
3. Optionally exclude ambiguous characters (like 0 and O) if the password must be typed manually
4. Enter any specific characters you want to exclude, such as characters not supported by a website
5. Click Generate Password. Click Copy next to any password to add it to your clipboard
6. Store the password in a password manager, not in a text file or browser note

Example Passwords

Example 1:Rachel, a freelance designer in Portland, needs a password for her banking portal. She generates a 20-character password with all character sets enabled, producing approximately 131 bits of entropy. Example output: tX7!kM2#pLqW9&vRnJ4@. At one trillion guesses per second, this would take longer than the age of the universe to crack by brute force. She stores it in her password manager and never needs to type it manually.

Example 2: Tom, a developer in Seattle, needs a password he can type on a phone keyboard for a low-risk account. He generates a 20-character password with lowercase and uppercase only, no ambiguous characters, producing approximately 114 bits of entropy. Example output: mRpkTvWsLnqHjXdBfYcG. This is easier to type while still being extremely difficult to crack. For URL-safe encoding, he uses our URL Encode / Decode tool.

Example 3: A startup CTO in Austin generates a 32-character password with all character sets for the company's AWS root account, producing approximately 210 bits of entropy. This exceeds NIST recommendations and is effectively uncrackable. She stores it in a hardware security key and enables multi-factor authentication. For network configuration, she also uses our IP Subnet Calculator.

Real World Scenarios

Creating Unique Passwords for Every Account

The single most important password security practice is using a different password for every account. If one service is breached, attackers cannot use those credentials to access your other accounts. This practice, called credential isolation, prevents the cascade effect that turned the 2024 retail breach into a disaster for the Cleveland accounting firm. Generate a new password here for each new account you create.

Setting Up a Password Manager

A password manager stores all your random passwords securely behind one strong master password. Use this generator to create the strongest possible master password, since it is the only one you need to remember. NIST SP 800-63B-4 recommends allowing passwords up to at least 64 characters, which means you can use a long passphrase as your master password for easier memorization while maintaining high security.

Generating API Keys and Tokens

Developers use this tool to generate random API keys, session secrets, and configuration tokens for applications where a cryptographically random value is needed quickly. The Web Crypto API ensures the values are suitable for security-sensitive applications. For encoding API responses, use our Base64 Encode / Decode tool.

Common Mistakes to Avoid

• Reusing passwords: A strong password reused across multiple sites is only as secure as the weakest site. One breach exposes all your accounts. The 2025 Verizon DBIR found stolen credentials were the initial access vector in 22% of confirmed breaches.
• Storing passwords in plain text: Text files, spreadsheets, and sticky notes are all insecure. Use a reputable password manager that encrypts your vault locally or in the cloud.
• Using only numbers or only letters: A 12-digit numeric PIN has only 40 bits of entropy. The same length with full character sets has nearly twice as much. NIST emphasizes length over complexity, but character variety still increases entropy per character.
• Ignoring NIST guidance on composition rules: NIST SP 800-63B-4 states that verifiers SHALL NOT impose composition rules (requiring mixtures of character types) for passwords. Length and blocklist screening are more effective than requiring special characters. However, randomly generated passwords naturally include variety without needing rules.
• Forcing periodic password changes: NIST SP 800-63B-4 states that verifiers SHALL NOT require subscribers to change passwords periodically. Instead, force a change only if there is evidence the password has been compromised.

Limitations of This Generator

This generator produces random passwords using the Web Crypto API, which provides cryptographically strong randomness. However, a strong password is only one layer of security. It does not replace multi-factor authentication, which NIST recommends for any sensitive account. The generator does not check passwords against breach databases (NIST recommends comparing passwords against a blocklist of known compromised passwords). It does not evaluate whether a website stores passwords securely using salted hashing. It cannot prevent phishing attacks, where users are tricked into entering passwords on fake websites. For comprehensive account security, combine strong passwords with MFA, a password manager, and security awareness. For related tools, try our Base64 Encode / Decode, URL Encode / Decode, or IP Subnet Calculator.

Authoritative Research and Resources

• NIST SP 800-63B-4: Digital Identity Guidelines published in August 2025 is the current federal standard for password authentication. It requires a minimum of 15 characters for single-factor passwords, recommends allowing up to 64 characters, prohibits composition rules, and mandates blocklist screening against known compromised passwords.
• Verizon 2026 Data Breach Investigations Report analyzes thousands of confirmed breaches annually. The 2026 report found ransomware in 48% of all breaches (the highest in DBIR history) and system intrusion accounting for 60% of all breaches. Stolen credentials remain a primary initial access vector.
• CISA: Secure Our World is the Cybersecurity and Infrastructure Security Agency's public awareness program recommending four key steps: use strong passwords, enable MFA, recognize and report phishing, and update software regularly.