UUID Generator

How to use the uuid generator

1. Choose how many UUIDs you need.
2. Pick uppercase or hyphen options.
3. Click Generate, then Copy all.

About this tool

A UUID, also called a GUID, is a 128-bit identifier that is unique for practical purposes. Version 4 UUIDs are random, so they are safe to generate on the client with no coordination. Create up to 500 at once and copy them all.

What a UUID looks like

A UUID is 32 hexadecimal digits shown in five groups: 8-4-4-4-12, for example f47ac10b-58cc-4372-a567-0e02b2c3d479. In a version 4 UUID, the first digit of the third group is always 4, and the first digit of the fourth group is 8, 9, a or b. The other 122 bits are random.

Will two ever collide?

With 122 random bits there are about 5.3 × 10^36 possible values. You would need to generate billions of UUIDs every second for many years before a collision became likely, so for ordinary applications you can treat every UUID as unique without checking the database.

Version 4 or a time-ordered UUID?

Random UUIDs are scattered, which can slow down inserts into a database index because new rows land in random places. Newer time-ordered versions, such as version 7 in RFC 9562, begin with a timestamp so new IDs sort roughly in creation order. This tool generates version 4, which is the most widely supported and a good default.

Good uses, and one warning

• Primary keys and record IDs created on the client or in several services without coordination.
• File names, correlation IDs for logs, and idempotency keys.
• Test data and fixtures, where you can generate hundreds at once.
• Do not rely on a UUID as your only secret. For API keys and session tokens use a purpose-built secure token of sufficient length.

Frequently asked questions