Random UUID
|v4
eb4d5be2-ee8e-4c45-8903-4402c09f5e30
Time based UUID
|v6
1f11398d-bf96-6f30-985a-5d5337799893
UUID v7
|Time + Random
Uses a 48-bit Unix epoch timestamp (millisecond precision) followed by random bits. Time-sortable and optimized for better database indexing than V1. Considered the modern best practice.
019c9d75-c5a3-7209-b1d1-1ae49791f736
UUID v6
|Reordered Time-based
Time-based like V1 but reorders the bits to be monotonically increasing (better for database indexing). Does not expose the MAC address (often uses a random node ID instead).
1f11398d-bf96-6f31-8e57-3e9e5f79af5d
UUID v4
|Random (Pseudo-random numbers)
Maximum unpredictability and privacy. Not sortable by time. Higher (but still very low) theoretical collision chance compared to time-based.
64aa0932-9a56-4735-8918-2db0b7776ad8
UUID v1
|Time-based + MAC Address
High uniqueness, sortable by time. Privacy concern due to including the generating machine's MAC address.
dbf96f32-1398-11f1-985a-5d5337799893