Random String Generator
Use this free online Random String Generator to build cryptographically random tokens, API keys, hex strings, session IDs, invite codes and one-off identifiers. It is useful for developers mocking up test data, sysadmins generating service-account secrets, marketers creating unique promo codes, security teams seeding new authentication tokens, and anyone who needs a string that nobody could guess. Pick a length, pick a character set (alphanumeric, hex, base64 or your own) and the tool produces fresh strings on every click. Generation uses the browser's Web Crypto API, the same cryptographically secure source of randomness used by HTTPS, so the output is suitable for real production use.
How to Use This Random String Generator
Generating a string is one slider and one click.
- Set the desired length using the slider — 32 characters is a good default for tokens.
- Pick the character set — alphanumeric, hex, base64, URL-safe, or define your own custom pool.
- Optionally pick how many strings to generate at once — useful for bulk seeding.
- Click Generate to produce the string(s).
- Click Copy to send the string to your clipboard, ready to paste into your code, secret store or config file.
How This Random String Generator Works
A random string is built by drawing each character from a pool of allowed characters using a strong source of randomness. The generator uses the browser's crypto.getRandomValues() API, which fills a typed array with values from the operating system's cryptographically secure pseudo-random number generator — the same source that powers HTTPS and modern key generation. For each character of the requested length, the generator picks a random index into the chosen character pool and appends that character to the output. Common pools are pre-defined: alphanumeric (62 characters covering A-Z, a-z, 0-9), hex (16 characters covering 0-9, a-f), base64 (64 characters covering A-Z, a-z, 0-9, +, /), and URL-safe base64 (replaces + and / with - and _). The custom pool option lets you define any character set, which is useful for invitation codes that exclude visually confusing characters like 0/O. Bulk generation runs the same loop multiple times and lists every result. Output is suitable for production secrets, API keys, session identifiers and one-off tokens; it is never transmitted, logged or cached, so you can safely use it for genuinely sensitive credentials.
Last updated: May 2026.
Frequently Asked Questions
Are these strings cryptographically secure?
Yes — they use the browser's crypto.getRandomValues(), the same RNG used to generate encryption keys.
What's the difference between UUID v4 and a random string?
UUID v4 is a 128-bit random value formatted in a standard way (8-4-4-4-12 hex with version/variant bits set). Use UUIDs when interoperability matters; use plain random strings when you just need uniqueness.
Can I use these for passwords?
Yes, but the password generator is purpose-built and shows the password as a unit. The string generator produces a list of values — convenient for tokens, less so for memorable passwords.
How likely are collisions?
For UUIDs, astronomically unlikely (1 in 2^122). For shorter random strings, the birthday paradox applies — but at 16+ alphanumeric characters, collisions are still effectively impossible at small scales.
What's the maximum length supported?
512 characters per string and 100 strings per generation. That's far more than any realistic use case.