Random String Generator – Create Custom Random Text
Generate random strings with customizable length and character sets.
How to use this random string generator
- Drag the length slider to choose how many characters you want, from 1 to 1,000
- Check the boxes for which character types to include: uppercase, lowercase, numbers, and/or symbols
- Alternatively, tick "Use custom characters" and type the exact set of characters you want the string built from
- Click "Generate Random String" to produce a new value using the cryptographically secure random source
- Click the copy button to copy the generated string to your clipboard
- Adjust the length or character options and click generate again anytime you want a different result
Frequently Asked Questions
How are random strings generated?
Strings are generated using cryptographically secure random number generation (Web Crypto API). Each character is randomly selected from your chosen character set.
What can I use random strings for?
Random strings are useful for API keys, session tokens, unique identifiers, passwords, and any application requiring unpredictable strings.
Can I use custom characters?
Yes, you can enable custom character mode and specify exactly which characters to use. This is useful for generating strings with specific requirements.
Related Tools
A random string generator helps developers, system administrators, and everyday users create unpredictable text for API keys, temporary passwords, session tokens, unique identifiers, and test data. It's useful whenever you need a value that's difficult to guess, such as generating a placeholder secret while scaffolding an application, creating a one-off passphrase to share with a teammate, or producing sample data for testing input validation. Unlike simply mashing the keyboard, this tool draws each character from a cryptographically secure random source and lets you control exactly which character types are included, or supply your own custom character set entirely. Everything is generated locally in your browser, so the strings you create are never transmitted anywhere, making it safe to generate values you intend to use as real secrets.
What is random string generator?
This tool builds a character set from the options you select - uppercase letters, lowercase letters, numbers, and symbols - or uses a custom set of characters you type in yourself. It then uses the Web Crypto API's getRandomValues function to fill an array with cryptographically secure random byte values, one for each character position, and maps each byte to a character in your chosen set using a modulo operation. This is fundamentally different from Math.random(), which is not designed to be unpredictable enough for security-sensitive use. You can generate strings from 1 to 1,000 characters long, and the result updates only when you click the generate button, giving you full control over when a new value is produced.
Common use cases
- Generating a temporary API key or secret token while scaffolding a new application
- Creating a one-off strong password or passphrase to share with a teammate through a secure channel
- Producing unique identifiers for database records, file names, or test fixtures
- Building sample or test data with specific character constraints for input validation testing
- Creating a random session token or CSRF-style value for prototyping authentication flows
- Generating a custom-alphabet string, such as numeric-only PINs or hexadecimal-only values, using the custom character option
Limitations and common mistakes
- Randomness comes from the Web Crypto API's getRandomValues, which is cryptographically secure, but the character-selection step uses a modulo operation, which can introduce an extremely slight statistical bias when the charset length doesn't evenly divide 256 - negligible for nearly all practical uses but worth noting for rigorous cryptographic applications
- If "Use custom characters" is enabled with an empty field, or every character type checkbox is deselected, generation is blocked until at least one character source is provided
- The tool does not enforce that generated strings meet any particular complexity policy (such as requiring at least one number and one symbol) - it simply draws randomly from the selected set
- Generated strings are only as safe as the environment they're copied into; anything copied to your system clipboard may be accessible to other applications until it's overwritten
- This tool does not automatically regenerate as you change settings - you must click "Generate Random String" again to produce a new value