Whenever a system needs to label something with a guaranteed-unique identifier — a database record, an API request, a file, or a user session — it often reaches for a UUID. Our free UUID generator creates cryptographically random version 4 UUIDs instantly, one at a time or in bulk, right in your browser.
What Is a UUID?
A UUID (Universally Unique Identifier), sometimes called a GUID (Globally Unique Identifier), is a 128-bit value usually written as 32 hexadecimal digits in five groups separated by hyphens, like this:
f47ac10b-58cc-4372-a567-0e02b2c3d479
The defining feature of a UUID is that it is unique without any central coordination. Two different systems can each generate UUIDs and be virtually certain they will never collide — which makes UUIDs ideal for distributed applications.
What Is a UUID v4?
There are several UUID versions, but version 4 is by far the most common. A UUID v4 is generated almost entirely from random data. It has 122 bits of randomness, which means the chance of two UUIDs ever colliding is so small it can be safely ignored in practice. Our generator uses your browser's crypto.getRandomValues() — a cryptographically secure random number generator — to produce them.
How to Generate UUIDs Online
- Set how many UUIDs you want — generate one or hundreds at once.
- Choose uppercase or lowercase formatting.
- Click Generate.
- Copy a single UUID or copy them all together.
Everything happens locally in your browser, so no identifiers are ever sent to a server.
Common Uses for UUIDs
Database primary keys — Use UUIDs instead of auto-incrementing integers so records can be created across multiple servers without conflicts.
API request IDs — Tag each request with a UUID to trace it through logs and debugging.
File and object names — Guarantee unique filenames for uploads without checking for collisions.
Session and transaction tokens — Label sessions or transactions uniquely.
Why Use UUID v4?
UUID v4 is popular because it requires no special inputs — no MAC address, no timestamp, no namespace. It is purely random, which makes it simple to generate anywhere and avoids leaking information like the time of creation or the machine that made it. For the vast majority of applications, v4 is the right choice.
Frequently Asked Questions
Is the UUID generator free? Yes — it is free, requires no sign-up, and runs entirely in your browser.
Are the UUIDs truly random?
Yes. They are generated with crypto.getRandomValues(), a cryptographically secure random source, giving version 4 UUIDs 122 bits of randomness.
Can I generate many UUIDs at once? Yes. Set the count and the tool will generate up to a hundred UUIDs in one click, with a copy-all option.
What is the difference between a UUID and a GUID? They are the same thing. GUID is Microsoft's term for a UUID; both refer to the same 128-bit unique identifier format.
Need a unique ID right now? Generate a UUID v4 instantly and copy it with a click.