How to use the uuid generator
- 1Choose version 4 for random IDs or version 7 for IDs that sort by creation time.
- 2Set how many you need, up to 1,000.
- 3Choose uppercase, hyphens or braces to match your system.
- 4Copy one, copy all, or download the list.
What a UUID is
A UUID (universally unique identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits, for example 3f2b8c1e-4d5a-4b6c-9e7f-0a1b2c3d4e5f. UUIDs can be created anywhere without a central server and are practically guaranteed never to repeat.
Version 4 or version 7?
- Version 4 is 122 bits of randomness. It is the most widely supported choice for IDs, tokens and keys.
- Version 7, defined in RFC 9562, starts with the current time in milliseconds followed by random bits. New IDs sort after older ones, which keeps database indexes efficient when UUIDs are used as primary keys.
How they are generated
Both versions use your browser's cryptographic random number generator. Nothing is sent to a server, and the IDs exist only on your device until you copy them.
Formatting
Hyphens and lowercase are the standard form. Some systems, such as Windows registry entries, expect uppercase with braces. Removing hyphens gives a compact 32-character string.
Frequently asked questions
Can two UUIDs ever be the same?
In theory yes, but the chance is so small it can be ignored. You would need to generate billions of version 4 UUIDs every second for many years to expect a single collision.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier format.
Which version should I use for database keys?
Version 7 is usually better for primary keys, because time-ordered values insert efficiently into indexes. Version 4 is fine for everything else.
Should I use UUIDs as passwords or secret tokens?
For secrets, use a dedicated random token or password generator. UUIDs are designed to be unique, not to be kept secret.
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