UUID Generator

About This Tool

This UUID generator online produces universally unique identifiers (also known as GUIDs) — 128-bit labels used to uniquely identify objects across distributed systems. The UUID v4 format generates its value using random or pseudo-random numbers, making collision extremely unlikely — the probability of generating two identical UUIDs is astronomically small, approximately 1 in 5.3 × 10^36.

UUIDs are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The 4 in the third group indicates version 4, and the y position is constrained to 8, 9, a, or b to indicate the variant.

This tool uses the browser's native crypto.randomUUID() function (available in all modern browsers) which generates cryptographically strong random UUIDs. No external library is used. The UUIDs are generated entirely locally — they are never transmitted to any server.

The bulk generator allows you to generate up to 100 UUIDs at once, all displayed in a scrollable list that you can copy to your clipboard with a single click.

How to Use

1. A UUID is generated automatically when the page loads.
2. Click Generate New UUID to get a fresh UUID v4.
3. Click Copy to copy it to your clipboard.
4. For bulk generation, enter a count between 1 and 100, then click Generate.
5. Click Copy All to copy all generated UUIDs to your clipboard, one per line.

Common Use Cases

• Primary keys for database records in distributed systems
• Unique identifiers for API resources, sessions, or tokens
• Filenames for uploaded files to avoid name collisions
• Idempotency keys for API requests
• Correlation IDs for tracking requests across microservices
• Unique IDs in NoSQL databases like MongoDB or DynamoDB

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. It is represented as 32 hexadecimal characters in the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed so that they can be generated independently by different systems without coordination and still be practically unique.

What is UUID v4?

UUID v4 generates its value using random or pseudo-random numbers. It is the most commonly used UUID version because it requires no external information (unlike v1 which uses the MAC address and timestamp). The probability of generating two identical UUID v4s is astronomically small — approximately 1 in 5.3 × 10³⁶.

What is the difference between UUID and GUID?

GUID (Globally Unique Identifier) is Microsoft's name for the same concept. UUIDs and GUIDs use the same format and are completely interchangeable. The term GUID is common in .NET and Windows development, while UUID is used in the broader standards context (RFC 4122).

Are UUIDs truly unique?

In practice, yes. The chance of a UUID v4 collision is so small it is effectively impossible in any real-world application. You would need to generate approximately 2.7 quintillion UUIDs before having a 50% chance of a single collision.

Can I use UUIDs as database primary keys?

Yes, and it is a common pattern — especially in distributed systems where multiple servers need to generate IDs independently without a central sequence. The tradeoff is that UUIDs are larger than integer IDs and slightly less efficient for indexed lookups, but this is rarely a practical concern.