What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in software systems.
The key advantage of UUIDs is that they can be generated independently across distributed systems without a central management authority, and the probability of duplicates is extremely low.
Key Version Differences
While there are several versions of UUIDs, the three most common in modern development are:
1. Version 4 (Random)
The most widely used format, composed of 122 bits of random data.
- Features: Unpredictable and easy to generate.
- Use Cases: Session IDs, User IDs, temporary tokens.
2. Version 7 (Unix Epoch timestamp + Random)
A newer standard (standardized in 2024) that includes a timestamp at the beginning.
- Features: Sortable by time (Lexicographically sortable).
- Use Cases: Database Primary Keys (PK). Ideal for maintaining B-tree index efficiency while ensuring uniqueness.
3. Version 1 (Timestamp + MAC Address)
Combines the generating machine’s MAC address with a timestamp.
- Features: Allows identifying when and where the ID was created.
- Use Cases: Legacy systems or scenarios requiring device-level uniqueness.
UUID vs. Incremental ID for Database Keys
| Feature | Sequential (Auto Increment) | UUID (v4) | UUID (v7) |
|---|---|---|---|
| Distributed | Difficult (Requires sync) | Easy (Decoupled) | Easy (Decoupled) |
| Predictability | High (Vulnerable) | Low (Secure) | Low (Secure) |
| Sort Order | By ID | Random | Chronological |
| DB Performance | High | Low | High (Efficient for B-trees) |
Generating UUIDs on DevToolKits
Our UUID Generator allows you to generate multiple UUIDv4s instantly and copy them with a single click. It’s perfect for creating test data during development.
💡 Tip: For security-critical applications (like API keys), always ensure you are using a generator with sufficient entropy.