UUID Generator

About this tool

Generate one or up to 100 random version-4 UUIDs at once, in your browser, using cryptographically secure randomness. Copy a single UUID or the whole batch, in lowercase or uppercase.

A UUID (universally unique identifier) is a 128-bit value written as 36 characters of hex and dashes. Version 4 UUIDs are random: 122 random bits mean the chance of two ever colliding is negligible for any realistic workload.

When to use it

• Assigning stable IDs to database rows, documents, or API resources without coordinating a counter across services.
• Generating correlation and request IDs for logs and distributed tracing.
• Creating test fixtures that need plausible unique identifiers in bulk.

Worked example

A generated UUID looks like 3f8a2c9e-7b41-4d06-9c2a-518e4b7d90f2. The 4 leading the third group is the version marker, and the first character of the fourth group encodes the variant. Generate 50 at once to seed a test database, copy all, and paste them straight into your fixture file.

Frequently asked questions

Can two generated UUIDs ever collide?

In theory yes, in practice no. With 122 random bits you'd need to generate about a billion UUIDs per second for roughly 85 years to reach even a 50% chance of one duplicate. Treat v4 UUIDs as unique.

What's the difference between UUID v4 and v7?

v4 is purely random. v7 embeds a millisecond timestamp in the leading bits so IDs sort roughly by creation time — friendlier to database index locality. If you don't have that specific need, v4 remains the universal default.

Does uppercase vs. lowercase matter?

No — UUIDs are case-insensitive, and the RFC recommends lowercase for output. Pick whichever your codebase conventions prefer; they identify the same value.

Are these UUIDs safe to use as secret tokens?

They're generated with secure randomness, so a v4 UUID is unguessable in practice. Still, purpose-built tokens (longer, from your framework's token generator) are the better habit for auth secrets — UUIDs are identifiers first.