UUID Generator
Free online UUID v4 / GUID generator. Generate up to 100 random Universally Unique Identifiers at once, with or without dashes. Runs entirely in your browser.
About the UUID Generator
A UUID (Universally Unique Identifier, also called GUID) is a 128-bit identifier like 3b241101-e2bb-4255-8caf-4136c566a962. Version 4 UUIDs are built from 122 bits of cryptographic randomness — so many possible values that collisions are practically impossible: even generating a billion per day for a century, the odds of a duplicate remain astronomically small.
Where UUIDs are used
UUIDs are the standard way to identify things without a central authority handing out numbers: database primary keys, API request IDs, distributed systems, file names, session tokens. Because anyone can generate one independently with no coordination, they scale across teams, servers and companies.
The generator uses your browser's crypto.randomUUID() where available and falls back to a standards-compliant implementation otherwise. All identifiers are created locally — nothing is transmitted or stored.
Frequently asked questions
What is the difference between a UUID and a GUID?
Practically none. GUID is Microsoft’s term for the same 128-bit identifier described by RFC 4122 as UUID. They are interchangeable in almost every system.
Can UUIDs collide (two being identical)?
Theoretically yes, practically no. A v4 UUID has 122 random bits. You would need to generate 2.7 quintillion of them before the collision probability reached even 50%.
Are version 4 UUIDs secure to use as tokens?
They are unpredictable and unique, which makes them reasonable for opaque IDs. But for security tokens like session IDs, prefer a purpose-built format with all 128 random bits (UUIDs spend 6 bits on version/variant flags) and an expiry policy.
What do the numbers in a UUID mean?
The "4" in the third group marks version 4 (random). The digit 8, 9, a or b starting the fourth group is the RFC 4122 variant marker. The rest is pure randomness.