What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. UUIDs are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens:
``
550e8400-e29b-41d4-a716-446655440000
``
The key property of UUIDs is that they are universally unique — you can generate them independently on any computer, at any time, and be virtually certain they won't collide with any other UUID ever generated.
UUID Versions
There are several UUID versions, each generated differently:
- UUID v1 — Generated from the current timestamp and the machine's MAC address. Unique but reveals information about when and where it was created.
- UUID v4 — Generated from random numbers. This is the most commonly used version and what this tool generates. The chance of collision is astronomically low (about 1 in 5.3 × 10^36).
- UUID v5 — Generated by hashing a namespace and a name using SHA-1. Useful for creating deterministic UUIDs from known inputs.
- UUID v7 — A newer format that combines timestamp ordering with randomness. Gaining popularity for database primary keys because they sort chronologically.
Why Use UUIDs?
Database Primary Keys — UUIDs are widely used as primary keys in databases because they can be generated without coordinating with a central server. This is essential for distributed systems.
API Identifiers — UUIDs make excellent identifiers in REST APIs because they're unique, hard to guess, and don't reveal information about your data (unlike sequential IDs).
Session Tokens — UUIDs are commonly used as session identifiers in web applications.
File Naming — When you need to ensure unique file names (like uploaded images), UUIDs prevent collisions.
Distributed Systems — In microservices and distributed architectures, UUIDs allow each service to generate unique identifiers independently.
How to Use This UUID Generator
1. Click "Generate" to create a new UUID v4.
2. Generate in bulk — set the quantity and generate multiple UUIDs at once.
3. Copy to clipboard with one click.
All UUIDs are generated in your browser using the Web Crypto API for proper randomness.
UUID vs. Other ID Formats
| Format | Length | Example | Use Case |
|---|
| UUID v4 | 36 chars | 550e8400-e29b-41d4-a716-446655440000 | General purpose |
|---|---|---|---|
| ULID | 26 chars | 01ARZ3NDEKTSV4RRFFQ69G5FAV | Sortable alternative |
| NanoID | Configurable | V1StGXR8_Z5jdHi6B-myT | Short, URL-friendly |
| Auto-increment | Variable | 1, 2, 3... | Simple databases |