What is a UUID and How to Generate One
UUIDs are everywhere in modern software — database IDs, API keys, session tokens. Here is exactly what they are and how to generate them.
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Use our free UUID Generator — generates cryptographically random v4 UUIDs instantly.
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 digits displayed in 5 groups separated by hyphens.
550e8400-e29b-41d4-a716-446655440000 xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx Where: M = version number N = variant
UUID versions explained
Time-based
Generated from current timestamp and MAC address. Reveals when and where it was created.
Name-based (MD5)
Generated from a namespace and name using MD5 hashing. Same input always produces same UUID.
Random (most common)
Generated from random numbers. Most widely used. Virtually impossible to predict or collide.
Name-based (SHA-1)
Like v3 but uses SHA-1 hashing. More secure than v3.
Generate UUID in JavaScript
// Modern browsers and Node.js 14.17+
crypto.randomUUID()
// "550e8400-e29b-41d4-a716-446655440000"
// Using uuid npm package
import { v4 as uuidv4 } from 'uuid';
uuidv4(); // "9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d"Generate UUID in Python
import uuid # Generate v4 UUID str(uuid.uuid4()) # "550e8400-e29b-41d4-a716-446655440000" # Generate v1 UUID str(uuid.uuid1())
When to use UUIDs
- ✓Database primary keys — no need for auto-increment
- ✓API resource identifiers — /users/550e8400-e29b-41d4-a716-446655440000
- ✓Session tokens and request IDs
- ✓File names for uploaded files
- ✓Distributed systems where IDs must be unique across machines