Random String Generator — Free Online Tool

A random string generator creates unpredictable strings for tokens, test fixtures, temporary passwords, or API keys. SWEDevTools: Prism uses the Web Crypto API to generate cryptographically random output, supports multiple character sets (alpha, numeric, alphanumeric, hex, base64, symbols) and a custom charset, and can generate multiple strings at once. Everything runs locally in your browser for speed and privacy.

Features

• Crypto-grade randomness: Uses crypto.getRandomValues() instead of Math.random() for better unpredictability.
• Preset + custom charsets: Use common sets like hex or base64, or define your own allowed characters.
• Bulk generation: Generate multiple strings in one run to speed up fixture creation and manual testing.
• No server round-trips: Runs locally for privacy and fast iteration during development.

Frequently Asked Questions

Is this safe for generating API tokens?

For many use cases, yes — it uses the Web Crypto API. For production, ensure you also store tokens securely (hash if appropriate) and enforce rotation/expiry.

What’s the difference between hex and base64?

Hex uses 0-9 and a-f (URL/file-name friendly). Base64 is more compact but may include + and /, which can be inconvenient in URLs unless encoded.

How do I generate URL-safe strings?

Use the alphanumeric charset or provide a custom charset that excludes characters like +, /, and =.

Can I exclude ambiguous characters like 0/O and 1/I?

Yes — choose custom and provide a charset that removes ambiguous characters for human-readable codes.

Is this the same as UUIDs?

No. UUIDs have a standardized format. Random strings are more flexible for constraints like only uppercase letters or fixed-length hex tokens.

Does the generator guarantee uniqueness?

Random generation reduces collision risk, but uniqueness isn’t guaranteed. Use sufficient length and a large charset, or enforce uniqueness at storage time.

Can I generate multiple lines at once?

Yes. Set count to generate a newline-separated list of strings.

Do you store the generated strings?

No. Everything runs locally in your browser.

What happened to smalldev.tools?

smalldev.tools is no longer available. Prism by SWEDevTools offers the same developer tools and more, with offline support, pipeline chaining, and completely free usage — no signup required.