How to generate UUIDs
- Choose version 4 (random) or version 7 (time-ordered).
- Set how many you need, up to 500, and the format: upper case, with or without hyphens.
- Copy them all or download a .txt file with one UUID per line.
Reading a UUID
Paste any UUID into the checker to see its version. For a v7 UUID it also shows the exact moment it was created, because the first 48 bits are a Unix timestamp in milliseconds.
| Version | Made from | Sorts by time |
|---|
| v4 | 122 random bits | No |
| v7 | 48-bit timestamp + 74 random bits | Yes |
Questions and answers
- Should I use UUID v4 or v7?
- Use v7 for database primary keys: it starts with a timestamp, so new rows land at the end of the index. Use v4 when an ID must reveal nothing, not even when it was made.
- Can two UUIDs ever collide?
- In practice, no. A v4 UUID has 122 random bits; you would need to generate billions per second for decades to expect one duplicate.
- Is a GUID the same as a UUID?
- Yes. GUID is Microsoft’s name for the same 128-bit identifier.
- Are the IDs generated on a server?
- No. They are created in your browser with the Web Crypto random generator, so nothing is logged anywhere.
Updated November 14, 2026