What Is a UUID
A UUID (Universally Unique Identifier) is a 128-bit identifier, with the standard format being an 8-4-4-4-12 hexadecimal string:
550e8400-e29b-41d4-a716-446655440000
The core value of UUID is "generating globally unique IDs without central coordination." guid and UUID are different names for the same concept.
Main UUID Versions
UUID v1 (Time-based + MAC Address)
Generated from the current timestamp and the machine's MAC address. Advantage: sortable. Disadvantage: exposes hardware address.
UUID v4 (Random)
Generated entirely from random numbers, the most widely used version. Advantage: simple to implement, no machine info leakage, extremely low collision probability. Disadvantage: not sortable.
UUID v5 (Namespace-based + SHA-1)
Generated from a namespace UUID and a name via SHA-1 hashing. Advantage: same input produces same result, reproducible.
Typical Use Cases
- Database primary keys: Distributed databases use UUID v4 as primary key to avoid auto-increment ID conflicts
- File naming: User-uploaded files named with unique identifiers to prevent overwriting by name collision
- Session ID / Token: Login sessions, API tokens generated with UUID v4
- Distributed task tracking: Microservice tracing uses UUID for identification
- Anonymous user identification: Statistics and tracking scenarios assign UUIDs to anonymous users
DocsAll UUID Generator Usage
DocsAll provides an online UUID generator that supports batch generation:
1. Select Version
Choose v1, v4, or v5 from the dropdown.
2. Set Quantity
Enter the number of UUIDs to generate, supporting 1-1000 at once.
3. Select Format Options
Uppercase/lowercase, with or without hyphens, with or without braces (GUID style).
4. Generate and Copy
Click the "Generate" button, results are displayed in a list, and can be copied with one click.
Usage Tips
- Use v4 for most scenarios — simple and reliable
- Choose v5 with a fixed namespace when reproducible IDs are needed
- For database primary keys, use v4 and index the field
- Removing hyphens for file naming is cleaner
Combined with Timestamp Conversion, Base64 Encode/Decode, and other tools, daily development identifier processing can be done efficiently.