UUID Generator
Generate random UUIDs
UUID Version
Generated UUIDs
What is a UUID?
A Universally Unique Identifier (UUID) is a 128-bit value used to uniquely identify resources across systems without central coordination. UUIDs are commonly used for database keys, API identifiers, distributed systems, and anywhere you need collision-resistant IDs.
Common UUID Versions
- v1 (time‑based): includes timestamp and node information. Good for ordering, but can leak timing/device details.
- v4 (random): generated using randomness; simple and widely used.
- v5 (name‑based): deterministically derived from a namespace + name via SHA‑1; useful when you need stable IDs for the same inputs.
Why Use UUIDs?
- Generate unique IDs client‑side without a central server.
- Reduce ID collisions across services and deployments.
- Great for distributed systems, offline workflows, and replication.
Examples
UUID v4 (random)
Example: 3f7c2b38-6c3e-4a5f-9f2a-2f0d8c9b9d31
UUID v5 (name‑based)
Given a namespace and name, v5 will always produce the same UUID for that pair.
Common Use Cases
Database Keys
Use UUIDs as primary keys to avoid coordination costs and to generate IDs on the client.
Public Identifiers
Safer than sequential IDs for URLs and API resources, making enumeration more difficult.
Privacy & Security
Generation happens locally in your browser. UUIDs are not inherently secret; avoid treating them as authentication tokens. Prefer random v4 for general use; use v5 when deterministic IDs are required.
Frequently Asked Questions
Is UUID v4 unique?
v4 uses randomness with an astronomically low collision probability for typical applications.
When should I use v5?
Use v5 when you need deterministic IDs (same namespace + name → same UUID), e.g., generating stable IDs for resources derived from known inputs.
Are UUIDs ordered?
Standard v4/v5 UUIDs are not ordered. If you need ordering, consider time-based IDs (v1 or ULIDs) and evaluate privacy implications.