Random String Generator
Generate cryptographically secure random strings with configurable length, charset, and bulk count
Interactive tool
Generator options
What is a Random String Generator?
A random string generator creates unpredictable sequences of characters using a cryptographically secure random source. The output is suitable for API keys, session tokens, secrets, and any case where guessability would be a security risk.
How to Use This Random String Generator
- 1Set the desired string length
- 2Toggle the character groups you want included
- 3Optionally exclude similar or ambiguous characters
- 4Set the count if you want a bulk batch
- 5Click regenerate to get a fresh batch, then copy or download
Key features
Cryptographically Secure
Uses the Web Crypto API (crypto.getRandomValues) so the output is suitable for security-sensitive contexts
Configurable Charset
Toggle uppercase, lowercase, digits, and symbols to match the rules of your downstream system
Custom Charset Override
Provide your own character set, for example hex digits, base32, or a domain-specific alphabet
Exclude Similar Characters
Optionally drop visually similar characters (i, l, 1, 0, O) for human-readable codes
Bulk Generation
Generate up to 100 strings at once for batches of test data, invitation codes, or coupons
Entropy Indicator
Total entropy in bits is calculated so you can confirm strength meets your security requirements
Copy and Download
Copy a single string or the whole batch to clipboard, or download as a text file
100% Private
Generation runs in your browser. Nothing is uploaded
Why Use a Random String Generator?
Predictable strings undermine security. Whether you need a one-time API key, a session token, or a coupon code, a strong random source keeps it unguessable. This generator uses the same cryptographic random source browsers use for their built-in security primitives.
Common use cases
- Creating API keys, secrets, and access tokens
- Generating one-time invitation or coupon codes
- Producing test data for unit and integration tests
- Seeding identifiers when UUIDs feel too long
- Creating temporary file names or upload IDs
- Generating verification codes for short-lived flows
- Producing throwaway passwords for service accounts
- Generating entropy-rich keys for symmetric encryption
How Strong is Strong?
128 bits of entropy is the modern minimum for most cryptographic purposes. 256 bits is appropriate for long-lived secrets. The entropy indicator in this tool tells you exactly how strong your output is so you can pick a length and charset that hits your target.
Charset and Character Exclusions
Including more character groups raises entropy per character, but excluding similar or ambiguous characters can help users transcribe codes correctly. Pick a charset that fits both the security requirement and the human factor.
Tips & best practices
Aim for at least 128 bits
For security-critical secrets, ensure the entropy indicator shows 128 bits or more
Use a custom charset for hex or base32
Provide ABCDEF0123456789 for hex, or A-Z plus 2-7 for base32 specifically
Exclude similar chars for printed codes
When users will type codes from paper or screens, drop similar chars to reduce mistakes
Generate in bulk for batches
Set a higher count and a single regenerate gives you the entire batch at once
Treat output as a secret
Strings generated here are not stored anywhere, but copy them carefully and avoid pasting into untrusted apps
Privacy & security
This random string generator runs entirely in your web browser using the Web Crypto API. Strings are never uploaded to any server, stored anywhere, or transmitted. All randomness happens locally on your device.
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Frequently Asked Questions
Is the output cryptographically secure?
Yes. The generator uses the Web Crypto API (crypto.getRandomValues), the same cryptographic random source browsers use internally. Output is suitable for API keys, secrets, and tokens.
Is my data sent to any server?
No. Generation runs entirely in your browser. Strings are never uploaded, stored, or transmitted to any server.
How long should my random string be?
Aim for at least 128 bits of total entropy for security-sensitive use. The entropy indicator updates as you change length and charset so you can hit your target.
How does the custom charset override work?
When you provide a custom charset, the toggle options are ignored and the generator picks characters only from your custom set. Use it for hex, base32, or domain-specific alphabets.
What is the difference between similar and ambiguous chars?
Similar characters look alike on screen or paper (i l 0 O 1). Ambiguous characters can be confused for syntax in some contexts (brackets, quotes, slashes). Exclude either when humans transcribe the output.
Can I generate strings in bulk?
Yes. Set the count slider up to 100 to generate that many strings in one click. Useful for invitation codes, test data, or batch credential creation.