What is the difference between a UUID and a GUID?

Nothing meaningful — GUID is Microsoft's name for the same 128-bit identifier. The formats are interchangeable.

Could two UUIDs ever collide?

In theory yes, in practice no. Version 4 has 122 random bits. You would need to generate a billion per second for around 85 years before a 50% collision chance — far beyond any realistic workload.

Should I use a UUID as a database primary key?

It depends. UUIDs let you generate keys without a round trip and avoid exposing row counts, but random values scatter writes across the index and hurt insert performance on large tables. UUID v7, which is time-ordered, addresses this.

Are these UUIDs cryptographically secure?

They use the browser's standard random generator, which is fine for identifiers. If a UUID is being used as an unguessable secret — such as a password reset token — use the Token Generator instead.

Key Generators

UUID Generator

Generates version 4 UUIDs — 128-bit identifiers that are randomly generated rather than derived from time or hardware. The format is 36 characters: 32 hexadecimal digits in five hyphen-separated groups.

Free, no signupRuns entirely in your browser

Input

Quantity

Result

fb5bedb1-5edc-46bf-81a9-fdc6e805ea96
dda08590-ef52-4ee6-98f3-e8c7554b6bcf
35035dab-6c51-4af6-a661-8ed6c9380143
e6430c1a-403a-4a76-9728-fea520a51d9d
683918b0-25c5-4d15-aafc-d775abf30c1f

About

What the UUID Generator does

The point of a UUID is that you can generate one anywhere without coordination and be confident it is unique. With 122 random bits, you would need to generate billions of UUIDs per second for a century before a collision became likely — which is why distributed systems use them instead of a central counter.

How it works

Using the UUID Generator

1Choose how many UUIDs you need.
2Each is generated with random values in the appropriate positions.
3The version digit is set to 4, marking it as randomly generated.
4The variant bits are set as the specification requires.
5Copy the resulting identifiers.

Use cases

What people use it for

Creating primary keys without a central sequence
Generating correlation IDs for tracing requests
Producing idempotency keys for API calls
Naming files or records uniquely across systems

FAQ

Frequently asked questions

6 related

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