Password Generator: Strong Random Passwords in One Click

What Makes a Password Strong

A strong password is one that is extremely unlikely to be guessed by an attacker, whether through brute force, dictionary lookup or credential stuffing from a prior breach. Three factors drive strength: length, the size of the character set the password is drawn from, and the randomness of the generation process. Each one matters, but length matters most.

The oldest advice to mix upper, lower, number and symbol came from early NIST guidance in the 2000s and was dropped in NIST Special Publication 800-63B in 2017. Modern research shows that users responded to those rules with predictable patterns such as Password1! which added almost no real entropy. The current guidance from NIST and OWASP is to require length, screen against known breached passwords and avoid forced composition rules.

A password is also only as strong as how it is stored. A perfect password reused across sites is weaker than two different passwords because a breach of one service compromises everywhere it was reused.

How Entropy Works

Entropy measures password strength in bits. Each bit doubles the number of guesses needed. A password drawn uniformly at random from a pool of P characters with length L has L times log2(P) bits of entropy. Example: a 16 character password from the 94 printable ASCII characters has 16 times log2(94), about 105 bits. For reference, 128 bits is considered post-quantum safe for the foreseeable future.

Not all randomness is equal. The browser Web Crypto API crypto.getRandomValues uses the operating system cryptographically secure pseudo-random number generator (CSPRNG). It is the same source trusted by browsers for TLS session keys. Math.random, by contrast, is a non-cryptographic PRNG and must never be used for passwords or tokens.

How to Use This Tool

Drag the length slider to set the number of characters.
Pick which character classes to include: upper, lower, number, symbol.
Toggle Exclude look-alikes if you will type the password by hand.
Click Generate to produce a new random password.
Read the strength bar to confirm the result is in the Very Strong band.
Click Copy, then paste into your password manager.

Common Use Cases

New account signups: Generate a fresh unique password rather than reusing an old one.
Rotating leaked credentials: Replace a password that appeared in a breach report.
API tokens and seed values: Use long alphanumeric output as a secret for internal systems.
Wi-Fi network keys: Produce a strong pre-shared key for WPA2 or WPA3.
Encrypted file passwords: Protect zip archives, PDF exports and backups.
Shared one-time credentials: Create a throwaway password for a demo account.

Common Mistakes

Patterns like Password1! or Qwerty123 that satisfy composition rules but are in every dictionary.
Reusing the same password across multiple sites.
Storing passwords in a plain text file, a sticky note or an unencrypted spreadsheet.
Picking short passwords because a site caps them at 12 characters. Use the maximum the site allows.
Sending passwords by email or messaging apps instead of a shared secret vault.

Why Password Managers Matter

A password manager solves the three biggest practical problems: generating unique passwords for every account, remembering them without reuse, and filling them only on the real domain to resist phishing. Open source options like Bitwarden and KeePassXC and commercial options like 1Password offer per-site records, strong master password derivation and encrypted sync.

The master password that unlocks the vault should be a long, unique passphrase of 5 to 7 random words. Combined with the vault owner's device biometrics, this produces a security posture that is far stronger than memorising unique random strings for dozens of sites.

Important A generated password is only as secure as the environment that received it. Avoid typing newly generated passwords into a device that may be compromised with keyloggers or malware. Prefer paste from a trusted password manager where possible, and never share a password through plain email or SMS.

Privacy

Generation happens in your browser using crypto.getRandomValues. The password never leaves your device, is not logged anywhere, and is not seen by this site's operators.

Frequently Asked Questions

How long should my password be?

NIST 800-63B recommends at least 8 characters, but practical guidance from security teams is now 14 to 16 characters minimum. For important accounts, 20 or more random characters is sensible and future-proof.

Do I really need special characters?

NIST stopped requiring forced character composition in 2017. Length gives more entropy than complexity. A 20 character random lowercase password is stronger than a 10 character mixed password.

Random password or memorable passphrase?

A fully random password stored in a password manager is strongest. If you must memorise, a 5 to 7 word diceware passphrase gives 65 to 90 bits of entropy and is easier to type.

Is bcrypt or Argon2 better for hashing passwords on a server?

Argon2id is the current recommendation from the Password Hashing Competition and OWASP. bcrypt is still acceptable but has a 72 character truncation limit. Never use raw SHA or MD5 for passwords.

Do password managers help?

Yes. A good password manager generates unique strong passwords per site, fills them automatically and resists phishing by matching against the real domain. The security win far outweighs the small risk of the manager itself being breached.

How long would a 16 character password take to crack offline?

A 16 character password drawn from 94 printable ASCII characters has about 105 bits of entropy. Even at 100 billion guesses per second, an exhaustive brute force would take trillions of years. Shorter or non-random passwords fall much faster.

Is the password generated here safe to use?

Yes. Passwords are generated with crypto.getRandomValues, a browser cryptographically secure random number generator. Nothing is uploaded or logged, so the password is known only to you.