Utilities & GeneratorsLive🔒 Private

Random String Generator

Generate random strings with custom length, charset, and format. Free online random string generator — cryptographically strong. No signup required.

How it works

The Random String Generator creates cryptographically-influenced random strings with configurable length and character set. Choose from alphanumeric, uppercase only, lowercase only, hex, numeric, or a custom character set of your own.

Random strings serve many purposes in software: temporary passwords, session tokens, API keys, test data identifiers, file name suffixes to prevent collisions, nonces for CSRF protection, and salt values for password hashing.

How to use it: set the desired string length, select the character set, choose how many strings to generate (up to 100 at once), and click Generate. The output can be formatted as one string per line, comma-separated, or as a JSON array for direct use in code.

Security note: this tool uses the browser's built-in `window.crypto.getRandomValues()` API to generate random bytes, which is cryptographically secure and suitable for security-sensitive uses like nonce generation. It is NOT the same as Math.random(), which is pseudorandom and unsuitable for security purposes.

Character set options: the default alphanumeric set (A-Za-z0-9, 62 characters) produces 62^n possible strings of length n. For a 16-character string, that's ~4.7 × 10^28 possibilities — sufficient for most token generation uses. For hex output (base 16), a 32-character string gives the same bit-length as a 128-bit UUID.

Frequently Asked Questions

Is this cryptographically secure?
Yes. The tool uses window.crypto.getRandomValues() — the same cryptographic random number generator used by browsers for TLS. This is suitable for nonce generation, CSRF tokens, and session IDs. It is NOT Math.random().
What character sets are available?
Alphanumeric (A-Za-z0-9), uppercase only (A-Z), lowercase only (a-z), hexadecimal (0-9a-f), numeric (0-9), symbols (!@#$%^&*), and a custom character set where you specify exactly which characters to use.
How many unique strings can it generate for a given length?
For alphanumeric (62 characters) at length 16: 62^16 ≈ 4.7 × 10^28 possible strings. For hex (16 characters) at length 32: 16^32 = 3.4 × 10^38, equivalent to 128-bit randomness (same as UUID v4).
Can I generate multiple strings at once?
Yes. Set the quantity to generate up to 1,000 strings per batch. Each string is independently generated. Output formats include one per line, comma-separated, JSON array, or space-separated.