What is a UUID and When Should Developers Use It?

The Problem with Incremental IDs

In traditional database design, we often used AUTO_INCREMENT integers (1, 2, 3...) as primary keys. While simple, this approach has drawbacks in modern distributed systems:

1. Enumeration Attacks: It's easy to guess the URL of resource #101 if you just viewed #100.
2. Merge Conflicts: Merging data from two different database shards is a nightmare if both have an ID 50.
3. Distributed Systems: You can't generate a unique ID on the client-side without asking the central server "what's the next number?".

Enter the UUID

UUID (Universally Unique Identifier) is a 128-bit label used for information in computer systems. The standard representation looks like this:

123e4567-e89b-12d3-a456-426614174000

The probability of colliding UUIDs is astronomically low—so low that you're more likely to be hit by a meteorite than generate a duplicate UUID v4.

UUID Versions: v1 vs v4

There are several versions of UUIDs, but the most common are:

UUID v1 (Time-based)

• How it works: Uses the current timestamp and the computer's MAC address.
• Pros: You can sort them by time; guaranteed uniqueness across machines.
• Cons: Reveals the time it was created and the machine's identity (MAC address), which can be a privacy concern.

UUID v4 (Random)

• How it works: Generated using random numbers.
• Pros: Completely anonymous; easiest to implement.
• Cons: Not sortable by creation time (unless you store a separate timestamp).

wowfree's UUID Generator defaults to UUID v4 because it is the industry standard for most web applications, safer for privacy, and collision-resistant enough for virtually any use case.

When to Use UUIDs?

• Public URLs: Hide the total number of users or orders in your system.
• Offline First Apps: Generate IDs on the client device before syncing to the server.
• Microservices: allow different services to create objects without coordinating with a central ID authority.

Generate UUIDs Instantly

Need a batch of UUIDs for testing or database seeding? Use our free UUID Generator. You can generate hundreds of IDs at once, toggle hyphens, and copy them to your clipboard with one click.