Random String Generator

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1 to 512 characters, 32 by default.
Up to 100 values per run, each one generated independently.
Custom characters are appended to the checked sets and duplicates are removed automatically.
Results
No results yet, use the button above to generate.
Privacy Everything is generated and analysed locally in your browser. Your input and the results are never uploaded and never stored.

Custom Character Sets and Quantity

What is the random string generator useful for?

Test data and random parameters

Load testing, unit testing, API debugging, and demonstrations often require batches of random strings with fixed lengths and character sets. Select the character types, set the length and quantity, and click Generate to create independent random strings.

Custom character sets

In addition to built-in lowercase letters, uppercase letters, digits, and symbols, you can enter a custom character set. For example, entering ABCDEF0123456789 generates test data limited to those characters. Custom characters are combined with the selected built-in character types, and duplicate characters are automatically removed.

Common presets

The generator provides seven presets: digits, lowercase, uppercase, lowercase plus digits, Hex, alphanumeric, and alphanumeric plus symbols. The Hex preset uses 0123456789abcdef.

Length and quantity

Each string can contain 1 to 512 characters, and up to 100 strings can be generated in one run. You can change the length and quantity at any time. New results are created only after clicking Generate or Regenerate, so changing parameters does not continuously generate random data.

Secure random source

Random data is generated with the browser's crypto.getRandomValues() API and rejection sampling is used to avoid distribution bias caused by simple modulo operations. If the browser does not support secure random numbers, the tool displays an error instead of generating insecure data.

Copy and export

Generated results can be copied individually, copied all at once, or exported as a TXT file. Each result has a sequence number, making it convenient to transfer the data into test datasets, configuration files, or API parameters.

How is this different from the password generator?

The random string generator focuses on flexible character sets and lengths. It does not require every selected character type to appear, making it more suitable for development, testing, and random data generation. Use the password generator when you need password-specific rules and strength analysis.

What can the random string generator do?

A batch random string tool for development and testing. Choose the length and quantity, select character types or enter a custom character set, and click Generate to create random results. Changing parameters only updates the configuration and does not automatically generate new strings.
  • Supports lengths from 1 to 512 characters and up to 100 results per run, with each result generated independently
  • Includes seven presets: digits, lowercase, uppercase, lowercase plus digits, Hex, alphanumeric, and alphanumeric plus symbols
  • Supports custom character sets, which are combined with selected character types and automatically deduplicated
  • Changing length, quantity, or character set does not continuously generate results; click Generate or Regenerate to create new data
  • Uses browser crypto.getRandomValues() with rejection sampling to avoid distribution bias from simple modulo operations
  • Results support individual copy, copy-all, and TXT export for test data, random IDs, and temporary parameters
Use the password generator when you need password rules and strength analysis. When you need random bytes encoded as Hex, Base64, or Base64URL, use the secure Token generator.
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