Loading...
Generate random strings with customizable length and character sets
Enter custom characters to use instead of the selected charset
Random string generator creates strings of specified length using selected character sets (letters, numbers, symbols). Essential for generating test data, placeholder content, unique identifiers, and temporary values that do not require cryptographic security.
Select your character set (uppercase, lowercase, digits, symbols), specify length, and generate. The tool uses JavaScript's Math.random() for quick generation. For each character position, it randomly selects from the available character pool. Multiple strings can be generated at once.
Math.random() provides pseudo-random numbers (not cryptographically secure). For secure tokens, use crypto.getRandomValues() or Web Crypto API. Character sets: A-Z (26), a-z (26), 0-9 (10), symbols (~32 common). Combined pool of 94 printable ASCII characters provides high entropy for long strings.
Create random names, IDs, or content for testing.
Generate 100 random usernames for load testingFill forms or databases with temporary random data.
Generate one-off unique strings for non-critical purposes.
Populate UI mockups with varied sample content.
function randomString(length, options = {}) {
const upper = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
const lower = 'abcdefghijklmnopqrstuvwxyz';
const digits = '0123456789';
const symbols = '!@#$%^&*()_+-=[]{}|;:,.<>?';
let chars = '';
if (options.uppercase !== false) chars += upper;
if (options.lowercase !== false) chars += lower;
if (options.digits !== false) chars += digits;
if (options.symbols) chars += symbols;
let result = '';
for (let i = 0; i < length; i++) {
result += chars.charAt(Math.floor(Math.random() * chars.length));
}
return result;
}
// Examples
randomString(10); // "Kj7mNx2pQr"
randomString(8, { symbols: true }); // "a#4Km!9x"
randomString(6, { digits: true, uppercase: false, lowercase: false }); // "847291"Build character pool from selected sets, then randomly pick from pool for each position.
Use random string generator for test data, placeholders, demo content, and non-critical unique identifiers. Never use for passwords or security tokens.
No! Math.random() is predictable. Use the dedicated password generator or crypto.getRandomValues() for security-sensitive applications. This tool is for test data, placeholders, and non-critical uses only.