What is a random string generator?
A random string generator creates a sequence by securely selecting characters from a chosen character set. You control the length, quantity, and whether the result can contain lowercase letters, uppercase letters, numbers, symbols, or your own characters.
Random strings are useful for test values, temporary identifiers, mock tokens, cache keys, anonymous record codes, and other development tasks. They are character sequences rather than readable sentences or paragraphs.
How to generate random strings
- Open Settings.
- Set the length and quantity.
- Choose Built-in characters and select the character types you need, or switch to Custom characters and enter your own character pool.
- Turn on Unique strings when results must not repeat within the current batch.
- Select Generate.
- Copy the newline-separated results or download
random-strings.txt.
Changing a setting clears the previous result so the displayed strings always match the current configuration.
Random string examples
Alphanumeric test ID
Use lowercase letters, uppercase letters, and numbers with a length such as 16:
g7K2qM9xP4vT8bN3Hex string
Switch to Custom characters and use:
0123456789abcdefURL-safe token
Use this custom character set:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_These examples describe settings only. The generated values change every time.
Character set options
Built-in mode provides lowercase letters, uppercase letters, numbers, and printable ASCII symbols. Lowercase, uppercase, and numbers are enabled by default, while symbols are optional.
Custom mode replaces the built-in character types. It can generate hexadecimal strings, numeric-only codes, URL-safe values, or strings limited to a project-specific alphabet. Repeated characters in the custom input are treated as one character in the pool.
Secure random strings
This tool uses the browser Web Crypto API rather than Math.random(). Random bytes are mapped to the selected character set with rejection sampling, which avoids the distribution bias caused by simple modulo mapping.
A secure random source does not make every result suitable as a production password, API key, session secret, or cryptographic key. Security also depends on length, character-set size, storage, rotation, and the requirements of the system using the value.
Unique random strings
Unique strings prevents duplicate values in the current generated batch. Before generating, the tool checks whether the selected character set and length can produce enough combinations.
The tool does not claim that a string is globally unique across different devices, users, or generations. Use a standard UUID when a system requires a standardized identifier with well-understood collision properties.
Random string vs related generators
| Tool | Best for |
|---|---|
| Random String Generator | Configurable character sequences, test data, temporary codes, and mock tokens |
| Password Generator | Account-password policies, strength requirements, and memorable password options |
| UUID Generator | Standardized identifiers with a very low collision probability |
| Random Text Generator | Words, sentences, paragraphs, and placeholder prose |
Random string generator FAQ
Can I generate letters and numbers only?
Yes. Keep lowercase letters, uppercase letters, and numbers enabled, and leave symbols disabled.
Can I use my own characters?
Yes. Select Custom characters in Settings and enter the exact character pool you want to use.
Can I generate multiple strings at once?
Yes. Quantity supports up to 1,000 strings, with one result per line.
Can generated strings contain duplicates?
Yes, unless Unique strings is enabled. With that option enabled, duplicates are prevented within the current batch.
Are the strings guaranteed to be globally unique?
No. Batch uniqueness does not guarantee uniqueness across different generations, browsers, devices, or users.
What is the difference between a random string and a UUID?
A random string uses a character set and length you choose. A UUID follows a standardized format intended for identifiers.
Is this the same as a password generator?
No. A password generator usually implements password-specific rules and strength guidance. This tool generates general-purpose character sequences.
What characters are URL-safe?
Letters, numbers, hyphens, underscores, periods, and tildes are commonly URL-safe in many contexts. Requirements vary by URL component, so use the exact alphabet expected by your system.
Is Math.random() secure enough for tokens?
No. Math.random() is not designed for security-sensitive random values. This tool uses crypto.getRandomValues() instead.
What are the generation limits?
Length supports 1–1,024 characters, quantity supports 1–1,000 strings, and the combined output is limited to 1,000,000 characters.