UUID Generator
Free online UUID v4 generator. Generate cryptographically random UUIDs instantly. Create up to 100 UUIDs at once. All processing happens locally in your browser.
Click "Generate" to get started
How to Use UUID Generator
Configure Settings
Choose how many UUIDs you need (1–100) and whether you want uppercase or lowercase output. UUIDs are case-insensitive, so this is purely a formatting preference.
Generate UUIDs
Click the "Generate" button to create cryptographically random UUID v4 identifiers. Each UUID is unique — the probability of collision is astronomically low.
Copy or Download
Use "Copy All" to copy generated UUIDs to your clipboard, or "Download" to save them as a .txt file for later use.
Example UUID
550e8400-e29b-41d4-a716-446655440000Each UUID is 36 characters, including 4 hyphens as separators.
Frequently Asked Questions
What is a UUID?
UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. A standard UUID looks like this: 550e8400-e29b-41d4-a716-446655440000. UUIDs are designed to be globally unique without requiring a central authority to generate them.
What is UUID v4?
UUID version 4 generates identifiers using random numbers. It's the most commonly used UUID version because it doesn't require a MAC address or timestamp. The format is: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where the 4 indicates version 4 and y is 8, 9, a, or b.
How likely is a UUID collision?
Extremely unlikely. With 122 random bits, you would need to generate about 2.7 × 10¹⁸ UUIDs to have a 50% chance of collision. To put that in perspective, generating 1 billion UUIDs per second would take about 85 years to reach that number.
When should I use UUIDs?
UUIDs are ideal for distributed systems, database primary keys, session IDs, file names, and any scenario where you need globally unique identifiers without coordination. They're especially useful in microservices architectures where multiple services need to generate IDs independently.
About UUID v4
UUID v4 is the most popular UUID version, generating 122 bits of random data. The remaining 6 bits are reserved for the version (4) and variant indicators. Our generator uses the Web Crypto API for cryptographically secure random number generation, ensuring each UUID is truly unique.
UUID Format Breakdown
- 8 hex digits — random
- 4 hex digits — random
- 4 hex digits — starts with '4' (version)
- 4 hex digits — starts with 8/9/a/b (variant)
- 12 hex digits — random