How to use the UUID Generator
- Choose v4 for a random ID or v7 for IDs that sort by creation time.
- Set how many you need and click Generate.
- Pick a format: hyphens or not, uppercase, braces, or ready-to-paste JSON and SQL lists.
- Click Copy or Download .txt. Paste any UUID in Check a UUID to see its version and creation time.
v4 or v7?
- Version 4 is 122 bits of pure randomness. It reveals nothing about when or where it was made, and it's the most widely supported.
- Version 7 (RFC 9562, 2024) starts with a millisecond timestamp, so new IDs sort after older ones. As database primary keys they keep indexes compact and inserts fast, unlike random v4 keys. The trade-off: anyone can read when a v7 ID was created.
Can two UUIDs ever be the same?
In practice, no. With v4 you would need to generate about 2.7 quintillion (2.7 × 1018) UUIDs to have a 50% chance of a single duplicate. These UUIDs come from your browser's cryptographically secure random generator, the same source used for encryption keys.
UUID vs GUID
They're the same thing. GUID (globally unique identifier) is Microsoft's name for a UUID. Use the Uppercase and {Braces} options to match the style Windows and .NET often show.
Anatomy of a UUID
0192f3c4-7a1b-7c3d-9e8f-0123456789ab
^ ^
| variant (8, 9, a or b)
version
Frequently asked questions
Are these UUIDs truly random?
v4 UUIDs use crypto.randomUUID() or crypto.getRandomValues(), your browser's cryptographically secure generator. They are not predictable.
Is a v7 UUID safe to expose?
It reveals its creation time to the millisecond. That's fine for most IDs, but use v4 if the timing of records is sensitive.
How many can I generate at once?
Up to 10,000 per click. Download them as a text file for large batches.
What are the Nil and Max UUIDs?
Special values with all bits 0 (<code>00000000-…</code>) or all bits 1 (<code>ffffffff-…</code>), sometimes used as placeholders.