Random String Generator – Generate Secure Strings

When to use this generator

You need placeholder IDs, coupon-style codes, or bulk test fixtures with a fixed alphabet.
You are mocking API responses or UI states where uniqueness matters more than cryptographic strength.
You want a readable charset (e.g. base32-style) without pulling in a library for a one-off script.

Real-world example

QA asks for fifty invite codes that avoid ambiguous characters. You set length 10, count 50, enable only uppercase + digits (or paste a custom charset like 23456789ABCDEFGHJKMNPQRSTUVWXYZ), generate, and paste the list into a spreadsheet—no server round-trip.

Common mistakes

Using output as long-term secrets or production session tokens—Math.random() is not cryptographically strong.
Charset too small at high length still gives guessable codes (e.g. only digits for a short OTP).
Custom charset with duplicates or accidental spaces skews probability; trim and dedupe mentally before generating.

Limitations of this tool

Randomness comes from the browser's non-crypto PRNG—use crypto.getRandomValues or your platform's secrets API for passwords, keys, and signing material.
No uniqueness guarantee against prior runs or collisions in distributed systems—use UUIDs or DB constraints when that matters.
It does not validate outputs against regex rules from your backend; it only produces strings from the charset you pick.

How to use Random String Generator

Set the string length

Enter how many characters the output should have. Common lengths: 8 (simple password), 16 (API token), 32 (session token), 64 (secret key).

Select the character set

Check the character types to include: uppercase (A–Z), lowercase (a–z), numbers (0–9), symbols (!@#$%^&*). More character types = stronger randomness per character.

Set the quantity

Enter how many strings to generate at once. Generate a batch of 100 test tokens or 10 promo codes in one click.

Apply exclusions (optional)

Exclude ambiguous characters (0, O, l, 1, I) that look similar in certain fonts — useful when generating codes that users must read and type.

Click Generate and copy

Strings appear instantly. Use the copy-all button for batch output, or copy individual strings. Each click generates a fresh set.

Random String Generator examples

Generate a strong temporary password

Input

Length: 16 · Uppercase + lowercase + numbers + symbols

Output

xK7!mR2@nP5$qT9#

A 16-character mixed-type string has 95¹⁶ ≈ 4.4 × 10³¹ possible values — brute-force infeasible with current technology.

Generate batch promo codes

Input

Length: 8 · Uppercase + numbers · No ambiguous · Count: 50

Output

ZX4K7MR2, QP9T3WN5, ... (50 codes)

Excluding ambiguous characters (0, O, 1, I) makes codes easier for customers to read from a printed receipt or voucher without typing errors.

Who uses Random String Generator?

Common real-world scenarios where this tool saves time.

Developers building web apps

Generate test data for user tables and token fields

Populate test databases with realistic-looking usernames, session tokens, or API key strings. Random strings of the right length and format help QA teams test authentication flows.

System administrators

Create temporary passwords for new user accounts

Generate random temporary passwords that meet complexity requirements before sending a 'set your password' onboarding email. Random strings ensure no predictable patterns.

Marketing teams

Create unique promo, coupon, and referral codes

Generate hundreds of unique short alphanumeric codes for discount campaigns, referral programs, or one-time vouchers — all unambiguous and non-sequential.

Frequently Asked Questions

How strong is a random string as a password?

Strength depends on length and character set size. A 12-character string using all 95 printable ASCII characters has 95¹² ≈ 5.4 × 10²³ combinations. At 10 billion guesses/second, cracking takes ~1.7 million years. Use 16+ characters for critical accounts.

What characters should I exclude for human-readable codes?

Exclude these visually ambiguous characters: 0 (zero) and O (letter O), 1 (one) and l (lowercase L) and I (uppercase i). Using only uppercase + numbers and excluding these 5 characters creates codes that users can read and type accurately from paper or receipts.

Is the output cryptographically secure?

This tool uses window.crypto.getRandomValues() — the browser's CSPRNG (Cryptographically Secure Pseudo-Random Number Generator). It is suitable for session tokens, temporary passwords, and codes that need unpredictability. It is not a substitute for a proper KMS (Key Management System) for production cryptographic keys.

What is the difference between random string and UUID?

A UUID (Universally Unique Identifier) is a standardised 128-bit string in a specific format (8-4-4-4-12 hex groups). A random string is unconstrained — any length, any character set. Use UUID for database primary keys and resource identifiers. Use random strings for passwords, tokens, and codes.