UUID & ULID Generator
Generate UUID v4, UUID v7, and ULID identifiers instantly
Interactive tool
What are UUIDs and ULIDs?
UUIDs (Universally Unique Identifiers) and ULIDs (Universally Unique Lexicographically Sortable Identifiers) are standardized formats for generating unique identifiers. UUID v4 uses random generation, UUID v7 includes timestamps for sortability, and ULID combines timestamp and randomness for both uniqueness and lexicographic ordering.
How to Use This ID Generator
- 1Select the ID type: UUID v4, UUID v7, or ULID
- 2Choose how many IDs to generate (1-1000)
- 3Optionally enable uppercase format
- 4Click "Generate IDs" to create identifiers
- 5Copy individual IDs or download all as a file
Key features
Multiple ID Types
Support for UUID v4, UUID v7, and ULID formats
Bulk Generation
Generate up to 1000 IDs at once
Instant Creation
Generate IDs instantly in your browser
Sortable IDs
UUID v7 and ULID include timestamps for sorting
Format Options
Choose between lowercase and uppercase formats
Copy & Download
Copy individual IDs or download all as a file
100% Private
All ID generation happens locally in your browser
Free Forever
No registration, no limits, completely free
Why Use UUIDs and ULIDs?
Unique identifiers are essential in distributed systems where centralized ID generation is impractical. They ensure no collisions occur even when generating IDs independently across multiple systems. UUIDs are the standard for random unique IDs, while ULIDs offer the advantage of being sortable by creation time, improving database performance.
Common use cases
- Database primary keys in distributed systems
- API request tracking and logging
- Session identifiers and tokens
- File naming and versioning
- Event tracking and analytics
- Message queue identifiers
ID Type Comparison
- UUID v4: Random 128-bit identifier, not sortable
- UUID v7: Time-based 128-bit identifier, sortable by creation time
- ULID: 128-bit identifier with timestamp prefix, lexicographically sortable
Which ID Type Should I Use?
Use UUID v4 for maximum randomness when sorting is not important. Choose UUID v7 or ULID when you need IDs that are sortable by creation time. ULID is more compact when represented as a string (26 vs 36 characters) and includes millisecond precision timestamps.
Tips & best practices
Use UUID v7 or ULID for databases
Sortable IDs improve database index performance compared to random UUID v4.
UUIDs are globally unique
The chance of collision is so small (< 1 in 2^122) that they are considered universally unique.
ULID is case insensitive
ULID uses Base32 Crockford encoding which is case insensitive and URL safe.
Store as binary for efficiency
In databases, store UUIDs as binary (16 bytes) rather than strings (36 bytes) for better performance.
UUID v7 includes timestamp
UUID v7 encodes Unix timestamp in milliseconds, making it sortable and time-queryable.
Privacy & security
This UUID and ULID generator runs entirely in your web browser. No data is sent to any server. All ID generation happens locally on your device using cryptographically secure random number generators.
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Frequently Asked Questions
What is the difference between UUID v4 and UUID v7?
UUID v4 is randomly generated with no time component, while UUID v7 includes a Unix timestamp in milliseconds, making it sortable by creation time. UUID v7 is better for database performance as it creates more sequential IDs.
What is a ULID and how is it different from UUID?
ULID (Universally Unique Lexicographically Sortable Identifier) is similar to UUID but uses Base32 encoding, making it more compact (26 vs 36 characters) and URL-safe. It includes a timestamp prefix for lexicographic sorting and is case-insensitive.
Are UUIDs truly unique?
Yes, for practical purposes. The probability of UUID collision is so astronomically small (less than 1 in 2^122 for v4) that they are considered universally unique. You would need to generate billions of UUIDs per second for many years to have a realistic chance of collision.
Can I use these IDs as database primary keys?
Yes, UUIDs and ULIDs are excellent for database primary keys, especially in distributed systems. Use UUID v7 or ULID for better database performance due to their sortable nature, which improves B-tree index efficiency.
Should I store UUIDs as strings or binary in databases?
Store UUIDs as binary (16 bytes) rather than strings (36 bytes) for better performance and storage efficiency. Most modern databases support native UUID types that handle this automatically.