📖 What is UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 8-4-4-4-12 hexadecimal characters. UUID v4 uses random numbers and has a 1 in 2^122 chance of collision — making it practically impossible to generate duplicates. UUIDs are used as database primary keys, session IDs and resource identifiers.
💡 Example
Output
550e8400-e29b-41d4-a716-446655440000
6ba7b810-9dad-11d1-80b4-00c04fd430c8
6ba7b811-9dad-11d1-80b4-00c04fd430c8
...
🛠️ Common Use Cases
- Database primary keys that work across distributed systems
- Unique session and authentication token generation
- Generating idempotency keys for API requests
- Naming uploaded files to avoid collisions
- Creating unique test data fixtures
❓ Frequently Asked Questions
What is the difference between UUID and GUID? ▾
They are the same thing — GUID (Globally Unique Identifier) is Microsoft's term for UUID. Both follow the same RFC 4122 standard.
Are UUID v4s truly unique? ▾
In practice yes — UUID v4 has 122 bits of randomness. To have a 50% chance of collision you'd need to generate 2.7 × 10^18 UUIDs. The probability of collision in any real system is astronomically small.
Which UUID version should I use? ▾
v4 (random) for general use. v1 for time-ordered IDs (includes timestamp). v7 (newest) for sortable time-based IDs in modern databases.
Is UUID good for database primary keys? ▾
Yes, but UUID v4 is not sortable which can hurt index performance. Consider UUID v7 or ULID for time-ordered database keys.
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