UUID Generator

Generate UUID v4 values instantly in your browser for databases, APIs, mock records and unique IDs.

About UUID Generator

This UUID generator creates random UUID v4 values instantly in your browser using the cryptographically secure Web Crypto API. No data is sent to any server, making it safe for generating sensitive identifiers like session tokens or access keys.

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. The standard text representation is 32 hexadecimal digits displayed in 5 groups separated by hyphens:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

The format breakdown:

8 hex digits - First group
4 hex digits - Second group
4 hex digits - Third group (starts with version number, 4 for random)
4 hex digits - Fourth group (first digit indicates variant)
12 hex digits - Fifth group

UUID Version Comparison

Version	Generation Method	Use Case
`v1`	Timestamp + MAC address	Time-ordered IDs (reveals generation time)
`v3`	MD5 hash of namespace + name	Deterministic IDs from strings
`v4`	Random numbers	General purpose (this tool)
`v5`	SHA-1 hash of namespace + name	Deterministic IDs (better than v3)

UUID v4 Uniqueness

UUID v4 uses 122 random bits, providing approximately 5.3 × 10³⁶ possible values. To put this in perspective:

You'd need to generate about 2.71 quintillion UUIDs to have a 1 in a billion chance of a single collision
If you generated 1,000 UUIDs every second, it would take about 85 years to reach a 50% chance of collision
The number of possible UUIDs is greater than the number of atoms on Earth

Common UUID Use Cases

Database Primary Keys: Especially in distributed databases where auto-increment won't work
API Resource Identifiers: Unique IDs for REST/GraphQL resources
Session Tokens: Secure, unpredictable session identifiers
Transaction IDs: Track operations across distributed systems
File Naming: Unique filenames in distributed storage (S3, etc.)
Analytics Events: Track user actions with unique event IDs
Test Data: Generate realistic mock data for development

Example UUIDs

550e8400-e29b-41d4-a716-446655440000
6ba7b810-9dad-11d1-80b4-00c04fd430c8
f47ac10b-58cc-4372-a567-0e02b2c3d479

How to Generate UUIDs

Click "Generate UUID": The tool will instantly create a new random UUID v4 value.
Review the UUID: The generated UUID appears in standard format (8-4-4-4-12 hexadecimal).
Copy the UUID: Click "Copy UUID" to copy the value to your clipboard.
Generate more: Click "Generate UUID" again anytime you need another unique value.

UUID Format Reference

Position:  xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
           1       2    3    4    5

Group 1: 8 hex digits (32 bits)
Group 2: 4 hex digits (16 bits)
Group 3: 4 hex digits (16 bits, starts with version '4')
Group 4: 4 hex digits (16 bits, variant indicator)
Group 5: 12 hex digits (48 bits)

Frequently Asked Questions

What is a UUID and how is it structured?: A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. The standard format is 32 hexadecimal digits displayed in 5 groups separated by hyphens: 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). UUID v4, the most common version, uses random numbers for 122 of the 128 bits.
How unique are UUID v4 values?: UUID v4 has 122 random bits, giving 2^122 (approximately 5.3 x 10^36) possible values. The collision probability is extremely low: you'd need to generate about 2.71 quintillion UUIDs to have a 1 in a billion chance of a single collision. For practical purposes, UUIDs can be considered unique.
What are common use cases for UUIDs?: Common UUID use cases include: database primary keys (especially in distributed systems), API resource identifiers, session IDs, transaction IDs, file naming in distributed storage, tracking events in analytics, and generating unique test data.
Is this UUID generator cryptographically secure?: Yes. This tool uses the browser's crypto.randomUUID() API, which is backed by a cryptographically secure random number generator (CSPRNG). The generated UUIDs are suitable for security-sensitive applications like session tokens and access keys.
What is the difference between UUID versions?: UUID has several versions: v1 (time-based + MAC address), v2 (time-based with user identity), v3 (MD5 hash-based), v4 (random), v5 (SHA-1 hash-based). Version 4 is most common because it doesn't require coordination and provides sufficient uniqueness for most applications.
Can I use UUIDs as database primary keys?: Yes, UUIDs are excellent for distributed database primary keys because they can be generated independently without coordination. However, consider using UUID v7 (time-ordered) if you need index-friendly sequential IDs, as random v4 UUIDs can cause index fragmentation.