Make a batch of UUIDs
Choose how many and a fresh batch appears. Regenerate draws a new one.
5 × UUID v4
Everything stays in your browser. Nothing is sent or saved.
How to use the UUID generator
- Enter how many UUIDs you need, from 1 to 50.
- Copy the list: one UUID per line, ready for a spreadsheet, a seed file or a test.
- Press Regenerate for a new batch. Every UUID is drawn fresh, so you can keep going.
How the UUID generator works
A version 4 UUID is 128 bits written as 32 hexadecimal digits in five groups of 8, 4, 4, 4 and 12. Six of those bits are fixed: the 4 that starts the third group says version 4, and the fourth group always starts with 8, 9, a or b. The other 122 bits come from your browser’s cryptographic random number generator.
Layoutxxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is 8, 9, a or b
Possible UUIDs2¹²² ≈ 5.3 × 10³⁶
Chance of a repeatabout n² ÷ 2¹²³ for n UUIDs
That is why any system can make its own IDs without asking a central server first: the chance of two ever matching is far too small to plan around.
- Random bits per UUID
- 122
- A one-in-a-billion chance of any repeat
- about 103 trillion UUIDs
- Making a billion UUIDs a second
- 86 years to reach an even chance
- An even chance of one repeat
- about 2.7 quintillion UUIDs
A batch of 50 from this page has about a 2 in 10³⁴ chance of holding a repeat.
UUID generator FAQ
What is a UUID?
A universally unique identifier: a 128-bit label written as 32 hex digits in five groups, like 3f2b8c1e-9d4a-4e7b-a1c5-6f0e2d9b8a47. Databases, APIs and file formats use them to name records without a central counter. Microsoft calls the same thing a GUID.
What are the other UUID versions?
Can I use a UUID as a password or a secret link?
A random version 4 UUID is hard to guess, but it isn’t built to be a secret, and other versions are easy to predict. For anything that must stay secret, use the password generator or your framework’s token function.
Should my URLs use a UUID or a slug?
A slug where people read the link, like a blog post or a product page. A UUID where you don’t want to show how many records there are, like an order or a support ticket. The slug converter turns a title into a clean slug.
How do I make test data with UUIDs?
Generate as many IDs as you need, then pair each one with a name or a paragraph from the lorem ipsum generator. Paste them into a seed file or a spreadsheet. Because they are random, a second batch never clashes with the first.
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