How to generate UUIDs
- Choose version 4 for fully random IDs, or version 7 for IDs that sort in the order they were created.
- Set how many you need, up to 1,000, and pick a format.
- Copy them or download them as a text file, one per line.
Version 4 or version 7?
A UUID is a 128-bit identifier written as 32 hexadecimal characters, such as 3f2b8c1e-7d4a-4f1e-9b2c-5e6a7d8c9f01. Version 4 fills almost all of those bits with random data, so two systems can create IDs independently without ever clashing.
Version 7 starts with the current time in milliseconds and fills the rest with random data. IDs made later sort after earlier ones, which keeps database indexes compact and makes records easy to order by creation time. Many developers now prefer it for primary keys.
Frequently asked questions
Are these UUIDs really unique?
For practical purposes, yes. Version 4 has 122 random bits, so you would need to make billions of UUIDs every second for many years before a duplicate became likely.
Is a UUID the same as a GUID?
Yes. GUID is Microsoft's name for the same thing. Some Microsoft tools show GUIDs in upper case and inside braces, which the format options can match.
How are they generated?
With your browser's cryptographic random number generator, the same one used for security keys. Nothing is sent to a server or stored.