DevToolbox

UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit value used to identify information without requiring a central coordinating authority. This tool generates version 4 (random) UUIDs using your browser's secure random number generator — you can create a single UUID or a batch of many at once.

Click "Generate UUID" to create one.

Your data stays in your browser — this tool runs entirely on the client side and nothing is uploaded to a server.

How to Use the UUID Generator

  1. Click "Generate" to create a single UUID, or set a quantity and click "Generate Multiple."
  2. Click "Copy" next to any UUID, or "Copy All" to copy the full list.
  3. Click "Clear" to reset the list.

What is a UUID?

A UUID is a 36-character string (32 hexadecimal digits plus 4 hyphens) formatted as 8-4-4-4-12 characters, such as `f47ac10b-58cc-4372-a567-0e02b2c3d479`. UUIDs are designed to be unique across systems and time without needing a central registry to hand them out.

UUID versions and why v4 is common

The UUID spec defines several versions with different generation strategies: version 1 is based on timestamp and network information, version 3/5 are based on hashing a namespace and name, and version 4 is based on random or pseudo-random numbers. Version 4 is by far the most commonly used in application development because it requires no external input or coordination — just a good source of randomness.

Collision considerations

A version 4 UUID has 122 random bits, giving an astronomically large number of possible values — roughly 5.3 undecillion. The probability of two randomly generated UUID v4s colliding is negligible for virtually any practical application, which is why they are safely used as database primary keys and distributed identifiers without central coordination.

Example

Example UUID v4
—
f47ac10b-58cc-4372-a567-0e02b2c3d479

Tips

  • UUID v4 is the right default choice unless you specifically need time-ordering or namespace-based determinism.
  • This tool uses the browser's cryptographically secure crypto.getRandomValues() API.

Frequently Asked Questions

Are UUIDs guaranteed to be unique?

Not mathematically guaranteed, but the probability of a collision with UUID v4 is so vanishingly small it is treated as unique for all practical purposes.

What are common uses for UUIDs?

Database primary keys, session identifiers, tracking request IDs across distributed systems, and unique file or object names.

Are these UUIDs generated securely?

Yes, this tool uses your browser's built-in cryptographically secure random number generator (crypto.getRandomValues), not a weak Math.random()-based approach.

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