UUID generator
Generate one or many random version 4 UUIDs in your browser, using the cryptographic random number generator.
Runs in your browser. Nothing you enter is uploaded.
What it does
A UUID is a 128-bit identifier written as 36 characters, such as 3f2b8c1e-9d4a-4f6b-8a2e-5c7d9e1f0a3b. Version 4 UUIDs are random, so any device can create one without asking a central server, and collisions are so unlikely that they can be ignored in practice.
How to use it
- Choose how many UUIDs you need, up to 500.
- Choose uppercase or no dashes if your system wants that form.
- Press Generate, then copy or download the list.
Worked example
A generated value looks like 9b2f6c1a-7e43-4d0a-b5f8-2c9e6a1d4f70. The 4 at the start of the third group marks version 4, and the first character of the fourth group is always 8, 9, a or b.
How it works
The tool uses crypto.randomUUID(), or crypto.getRandomValues() in older browsers. 122 of the 128 bits are random; the other 6 mark the version and variant.
Questions
Can two UUIDs be the same?
In theory yes, in practice no. With 122 random bits you would need to generate billions per second for many years to expect one collision.
Are these safe to use as secrets?
They are generated from a cryptographic source, but a UUID is meant to be an identifier, not a password or API key.
Are the UUIDs stored?
No. They are created in your browser and disappear when you leave the page.
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