How to use the UUID Generator
- Choose v4 (random) or v7 (time-ordered) and how many
- Pick a format: hyphens, uppercase or braces
- Copy one, copy all, or download as a text file
About this tool
A UUID (universally unique identifier, RFC 9562) is a 128-bit value written as 32 hex digits. Version 4 is 122 random bits, so the chance of a collision is negligible: you would need about 2.7 quintillion IDs for a 50% chance of a single duplicate. Version 7 starts with a 48-bit millisecond timestamp, so IDs sort by creation time. That keeps database indexes compact and is now recommended for primary keys.
Randomness comes from crypto.getRandomValues(), the browser’s cryptographically secure generator, not Math.random().
Frequently asked questions
UUID v4 or v7: which should I use?
Use v7 for database primary keys and anything that benefits from time order. Use v4 when the ID should reveal nothing, not even when it was created.
Are UUIDs and GUIDs the same?
Yes. GUID is Microsoft’s name for the same 128-bit format.
Can two people generate the same UUID?
In practice, no. v4 has 2¹²² possible values, so a duplicate is astronomically unlikely.
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