Random String Generator
100% private — runs on your device, never uploaded. Works offline once loaded.
Generate one or many random strings with full control over length and which character sets to include. Every string uses your browser's cryptographically secure random generator, so nothing is predictable and nothing leaves your device.
Why cryptographically secure randomness matters
Not all randomness is equal. JavaScript's Math.random() is a pseudo-random generator seeded from a small internal state; it's fine for shuffling a game deck but was never designed to be unpredictable, and its output can sometimes be reconstructed by an attacker who sees enough of it. This tool instead uses the browser's Web Crypto API (crypto.getRandomValues), which draws from the operating system's cryptographically secure entropy pool — the same source used to generate real encryption keys.
To keep the character distribution perfectly even, the generator uses rejection sampling: it discards any random byte that would bias the result toward certain characters, rather than using a naive modulo that quietly makes some characters more likely than others. The practical upshot is that every position in every string is drawn uniformly from the pool you chose.
Choosing length and character sets
The strength of a random string comes from two things: how many characters it's built from (the pool size) and how long it is. A 16-character string drawn from a 62-character alphanumeric pool has about 95 bits of entropy — far beyond what's practical to brute-force. Adding symbols widens the pool further, which is useful when a system demands special characters, though some legacy systems reject certain symbols.
- For passwords, 16+ characters with mixed case, digits and symbols is a strong default.
- For API keys or tokens, longer alphanumeric strings (24–40 chars) avoid symbol-escaping headaches in URLs and config files.
- For readable codes, digits-only or uppercase-only keeps things easy to type and dictate over the phone.
Common uses
Random strings show up everywhere in software and everyday admin: temporary passwords, password-reset tokens, API keys, session identifiers, invite and coupon codes, database seed values, test fixtures, and unique file suffixes. Generating a fresh batch and picking from it is quicker than inventing characters by hand — and far more secure, since anything a human types tends to fall into predictable patterns.
The Regenerate button produces an entirely new set each time, so you can keep clicking until you get strings that suit whatever length and format the target system expects.
Frequently asked questions
What's the difference from a password generator?
There's no real difference in the engine — the same secure random source powers both. This tool just exposes raw controls (length, count, character sets) so you can generate strings for any purpose, not only login passwords.
Why did I get a warning about character sets?
You need at least one set enabled (uppercase, lowercase, digits or symbols). With every set turned off there's no pool to draw characters from, so the tool asks you to pick one.
Are the strings ever repeated or logged?
No. Nothing is stored or logged. Each generation is independent, and once you navigate away the strings are gone from memory.
How long can the strings be?
Up to 512 characters each, and you can generate up to 100 at a time. That covers everything from short PINs to long high-entropy keys.
Can I use these for encryption keys?
The randomness is cryptographically secure, so it's suitable source material. That said, most encryption systems have their own key-generation routines expecting a specific byte format — use those where available, and use this tool for passphrases, tokens and secrets.
Will symbols break my system?
Some systems reject characters like quotes, backslashes or spaces. This tool's symbol set avoids quotes and backslashes, but if a target still complains, generate an alphanumeric-only string by turning symbols off.
Advertisement