UUID Generator
Generate UUID and ULID identifiers
25f6b182-1fef-44e3-9e3e-bc9ef16ed2dcHow to Use UUID Generator
- 1
Choose a UUID version if the option is available (v4 is the most common).
- 2
Click Generate to create a new UUID.
- 3
Click Copy to copy it to your clipboard, or generate multiple UUIDs at once.
About UUID Generator
Generate UUID v1, v4, v5 and ULID identifiers online. Bulk generate up to 1000 UUIDs. Free.
Best Use Cases
- •Generating unique IDs for database records in a new project
- •Creating test UUIDs for API testing and mock data
- •Generating ULIDs when time-sortable unique identifiers are needed
- •Bulk generating UUIDs for data migration scripts
- •Creating unique identifiers for tracking events in analytics systems
Examples
Database IDs
Generate a v4 UUID like 550e8400-e29b-41d4-a716-446655440000 to use as a primary key in your database.
Bulk generation
Set quantity to 100 and generate a batch of UUIDs for seeding a test database with unique records.
ULID option
Generate a ULID instead of UUID when you need IDs that are both unique and chronologically sortable.
Common Mistakes to Avoid
- !Using v1 UUIDs when v4 random UUIDs are more appropriate for most applications
- !Assuming UUIDs are always URL-safe without encoding them first
- !Generating UUIDs client-side for security-sensitive purposes like session tokens
Limitations
- –Browser-generated UUIDs use Math.random, not cryptographic randomness
- –Cannot generate v3 or v5 namespace-based UUIDs without providing a namespace
- –Bulk generation of very large quantities may slow down the browser
Frequently Asked Questions
What is UUID v4?
UUID v4 is randomly generated - the most commonly used version. It's a 128-bit number formatted as 8-4-4-4-12 hex characters.
What is the difference between UUID and GUID?
They are the same concept - Microsoft calls them GUIDs (Globally Unique Identifiers), while the standard term is UUID.
What is a UUID used for?
UUIDs are used as unique identifiers for database records, file names, session tokens, API request IDs, and distributed system components. They are designed to be unique across systems without a central coordinator.
What is the difference between UUID v4 and other versions?
UUID v4 is randomly generated and the most commonly used version. UUID v1 includes a timestamp and MAC address. UUID v5 is generated deterministically from a namespace and name. For most use cases, v4 is the right choice.
Can two generated UUIDs ever be the same?
In theory yes, but in practice the probability is astronomically small. A UUID v4 has 122 bits of randomness. You would need to generate approximately 2.7 quintillion UUIDs before having a 50 percent chance of a single collision.