Random String Generator

How to Use

1. Set the desired length of each string using the slider (1–128 characters). Longer strings have higher entropy.
2. Set the count — how many strings to generate at once (1–1000).
3. Choose a character set from the dropdown: alphanumeric, hex, numeric, alpha, lowercase, uppercase, base64, or custom.
4. If you select Custom, enter your own charset in the input field. The tool validates it for minimum length and duplicates.
5. Click the Generate button to create the random strings. Results appear in a scrollable list.
6. Use the Copy button next to each string to copy it individually, or Copy All to copy all strings at once.
7. Click Clear to reset the results.
8. Try a preset like API Key, Session Token, Hex Color, or Short Code for quick common configurations.

Cryptographic Security

This tool uses the Web Crypto API (crypto.getRandomValues) for all random number generation. This API is available in all modern browsers and Node.js environments, and it provides cryptographically secure random values suitable for security-sensitive operations. The random numbers are generated by the operating system's cryptographically secure pseudo-random number generator (CSPRNG), which draws from entropy sources like hardware noise, interrupt timings, and other unpredictable system events.

To ensure a uniform distribution over the chosen character set, the tool uses rejection sampling. This technique rejects random values that would introduce bias when mapping to the character set. Without rejection sampling, some characters in the charset would be slightly more likely than others, reducing the effective entropy. With rejection sampling, every character in the charset has exactly the same probability of being selected.

All generation happens entirely in your browser — no string is ever sent to a server, stored in a database, or transmitted over the network. This makes the tool safe to use even for generating API keys, access tokens, and other sensitive credentials. Once you close or refresh the page, all generated data is gone.

The tool also includes a built-in UUID v4 generator that creates RFC 4122-compliant UUIDs using the same cryptographic randomness source. UUIDs are widely used as unique identifiers in databases, distributed systems, and API responses. Additionally, the token generator produces URL-safe tokens using the Base64url encoding (A–Z, a–z, 0–9, -, _), which are safe to use in URLs, filenames, and query parameters.

Common Use Cases

• API Keys — Generate 32–64 character alphanumeric strings for API authentication. The high entropy ensures keys cannot be guessed or brute-forced.
• Session Tokens — Create long random tokens (64+ chars) for session management. The cryptographic randomness prevents session prediction attacks.
• Verification Codes — Generate short numeric codes (4–8 digits) for OTP (one-time passwords), email verification, or SMS authentication.
• Database IDs — Use hex strings as compact unique identifiers for database records, avoiding sequential IDs that can leak information.
• Coupon & Promo Codes — Generate human-readable uppercase codes for promotions, discount vouchers, and event tickets.
• Hex Color Codes — Generate random 6-character hex strings for color experimentation in design and prototyping.
• UUIDs — Generate RFC 4122-compliant UUID v4 identifiers for distributed systems, database primary keys, and API responses.
• URL-safe Tokens — Create Base64url-encoded tokens for use in URLs, query parameters, JWT tokens, and other web contexts where standard Base64 characters (+, /) would cause issues.