UUID Generator
Generate random v4 UUIDs — single or bulk.
4ce3d6bd-8dd1-4839-871d-e2befd6fd070What is a UUID?
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit identifier that is unique across time and space. UUIDs are standardized by RFC 4122 and are used in databases, distributed systems, and APIs to identify resources without requiring a centralized ID authority.
How to Use This Tool
The standard format consists of 32 hexadecimal digits displayed in 5 groups separated by hyphens: <code class="text-emerald-600 dark:text-emerald-400 bg-zinc-100 dark:bg-zinc-900 px-1 py-0.5 rounded text-xs">xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx</code>, where the "4" indicates version 4 (random).
Common UUID Use Cases
Frequently Asked Questions
- What is a UUID?
- A UUID (Universally Unique Identifier) is a 128-bit number used to identify resources without a central authority. The format is 8-4-4-4-12 hexadecimal digits, like 550e8400-e29b-41d4-a716-446655440000.
- Are v4 UUIDs truly unique?
- For practical purposes, yes. A v4 UUID has 122 random bits, giving 5.3 x 10^36 possible values. You would need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of a single collision.
- What is the difference between UUID versions?
- V1 uses the MAC address and timestamp (can leak device identity). V4 is purely random (most common). V5 uses SHA-1 hashing of a namespace and name. V7 (newest) combines a timestamp with random bits for sortability.
- Can I use UUIDs as database primary keys?
- Yes, but consider trade-offs. UUIDs prevent ID guessing and work across distributed systems, but they are larger (16 bytes vs 4-8 for integers) and can fragment B-tree indexes. UUID v7 solves the fragmentation issue by being time-sortable.
- Is the UUID generated on the server?
- No. UUIDs are generated entirely in your browser using the Web Crypto API (crypto.randomUUID), which provides cryptographically secure random numbers. Nothing is sent to any server.