How to generate UUIDs
- Pick the Version: 4 (random) or 7 (time-ordered).
- Enter How many you need, from 1 to 1000.
- Turn on Uppercase or turn off Keep hyphens if your system needs that format.
- Select Generate UUIDs, then Copy to put the list on your clipboard, one per line.
Select the button again for a fresh set. The settings are kept in the page address, so a link restores them.
What a UUID is
A UUID (universally unique identifier) is a 128-bit value used to name records, files, sessions and events without asking a central database for the next number. It is written in five groups: 8-4-4-4-12 hex digits. The first digit of the third group shows the version.
Version 4 and version 7
- Version 4 is 122 random bits plus the version and variant bits. It leaks nothing and is the most common choice.
- Version 7 puts a 48-bit millisecond Unix timestamp first, then random bits. UUIDs made later sort after earlier ones. That makes them far better database primary keys than v4, which scatter writes across an index.
In a bulk v7 list, IDs created in the same millisecond use a small counter so the list is still strictly in order. If you sort the lines as text, you get the creation order.
Tips
- Use v7 when you will sort or index by ID, and v4 when order must not be guessable.
- Some systems expect no hyphens or uppercase letters. Switch those options instead of editing by hand.
- Need a fingerprint of some content rather than a random ID? Use the hash generator.
- To pass an ID safely in a link, see URL encode and decode.
Privacy
The random numbers come from your browser’s secure generator, and the list is made on your device. Nothing is uploaded, stored or logged.