🔑 What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. Also known as GUID (Globally Unique Identifier) in Microsoft systems, UUIDs provide a standardized way to generate unique identifiers without requiring a central authority or coordination between systems.
This tool supports all UUID versions from v1 to v7, plus Nil (all zeros). UUID v4 (random - most common) generates random identifiers with an extremely low probability of collision - approximately 1 in 2^122. This means you could generate a billion UUIDs per second for 100 years and the probability of collision would still be only 50%. This makes UUIDs ideal for distributed systems where coordination is impractical.
Standard UUID format: 550e8400-e29b-41d4-a716-446655440000 (8-4-4-4-12 hexadecimal digits separated by hyphens, total 36 characters including hyphens).
🎯 How to Use the UUID Generator
- Select UUID Version: Choose from v1 to v7, or Nil (v4 Random is most common and pre-loaded).
- Click "Generate UUID": Instantly creates a new UUID - click multiple times to generate more.
- View All Formats: Each UUID is displayed in three formats - standard (lowercase), uppercase, and no hyphens.
- Copy Any Format: Click the copy button next to any format to copy it to clipboard.
- Use Immediately: Paste into your database, code, or configuration files.
🎯 Common Use Cases
🗄️ Database Primary Keys
Use UUIDs as primary keys in databases to ensure uniqueness across distributed systems, enable offline data creation, and avoid conflicts during data merging or replication.
🌐 API Resource Identifiers
Generate unique IDs for REST API resources, user sessions, API keys, and transaction references that need to be globally unique without database lookups.
📁 File and Document IDs
Create unique filenames, document identifiers, or version tracking IDs in file storage systems, content management systems, and cloud storage platforms.
🔐 Session and Token Generation
Generate secure session IDs, authentication tokens, request IDs for logging, and correlation IDs for distributed tracing across microservices.
☁️ Distributed Systems
Ensure unique identifiers across multiple servers, data centers, or cloud regions without requiring inter-system communication or centralized ID generation.
📱 Mobile & Offline Apps
Create records offline in mobile apps without connectivity, ensuring IDs won't conflict when syncing with servers later.
🔍 UUID Versions Explained
| Version | Generation Method | Use Case |
|---|---|---|
| v1 | Timestamp + MAC address | Sortable by time, but reveals hardware info |
| v3 | MD5 hash of namespace + name | Deterministic - same input always produces same UUID |
| v4 | Random (most common) | Fully random, no metadata, perfect for general use |
| v5 | SHA-1 hash of namespace + name | Like v3 but with more secure hashing algorithm |
| v6 | Reordered timestamp | Time-sortable like v1 but without privacy concerns |
| v7 | Unix timestamp milliseconds | Newest standard, excellent database performance and sorting |
| Nil | All zeros | Special UUID representing null or empty value |
Why v4? Version 4 UUIDs are the most widely used because they're simple (pure randomness), don't reveal any system information, and don't require timestamps or namespaces. They're perfect for most applications.
📐 UUID Format Options
Standard (lowercase)
550e8400-e29b-41d4-a716-446655440000 Most common format, lowercase hex with hyphens
Uppercase
550E8400-E29B-41D4-A716-446655440000 Same structure but uppercase (common in Windows/C#)
No Hyphens
550e8400e29b41d4a716446655440000 Compact format (32 characters, used in databases and URLs)
🔒 Privacy & Security
All UUID generation happens entirely in your browser using cryptographically secure random number generation methods. No UUIDs are sent to any server, logged, or stored - complete privacy and security. This tool uses secure browser APIs that provide unpredictable random values suitable for security-sensitive applications. However, UUIDs themselves are not secrets - they're identifiers, not passwords or encryption keys. ToolZone itself does not track, save, or transmit any of your data.
❓ Frequently Asked Questions
Can two UUIDs ever be the same? ▼
Theoretically yes, but practically no. The probability of generating a duplicate UUID v4 is approximately 1 in 2^122 - you'd need to generate billions of UUIDs per second for decades to have a realistic chance of collision.
Are UUIDs secure for authentication tokens? ▼
UUIDs are unpredictable and suitable for session IDs, but they're not encrypted or hashed. For authentication tokens requiring expiration or claims, use JWT or similar token standards instead.
Should I use UUIDs as database primary keys? ▼
UUIDs work well for distributed systems, offline-first applications, and avoiding ID conflicts during merges. However, sequential integer IDs often offer better database performance. Choose based on your specific needs.
What's the difference between UUID and GUID? ▼
No practical difference - GUID (Globally Unique Identifier) is Microsoft's term for the same concept. Both are 128-bit identifiers following the same RFC 4122 standard.
Which UUID version should I use? ▼
Version 4 (random) is most common and suitable for general purposes. Version 1 includes timestamps but reveals MAC addresses. Version 5 is deterministic (same input = same UUID). Version 7 is newer and time-sortable.
Can I generate UUIDs offline? ▼
Yes! This tool works entirely in your browser and doesn't require internet connectivity. UUIDs are generated locally using cryptographically secure random number generation.