Free tool · runs in your browser
UUID generator
Generate random version 4 UUIDs, one at a time or in bulk, and copy them in the format you need.
Quick answer
A UUID (universally unique identifier) is a 128-bit ID written as 32 hexadecimal characters in five groups, like 3f2b8c1e-9a4d-4c7e-b5f0-1d2e3a4b5c6d. Version 4 UUIDs are random; this tool creates them with the browser's cryptographically secure random generator, so the chance of two being the same is negligible.
How to use it
- Choose how many. From 1 to 500.
- Pick a format. Lowercase or uppercase, with or without dashes.
- Copy them. One per line, ready to paste.
Frequently asked questions
Can two UUID v4 values be the same?
In theory yes, in practice no: there are about 5.3 × 10^36 possible version 4 UUIDs.
What is the difference between UUID v4 and v7?
v4 is fully random. v7 starts with a timestamp, so values sort by creation time, which suits database primary keys.
Is a UUID the same as a GUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier.
How do I generate a UUID in JavaScript?
crypto.randomUUID() in modern browsers and Node.js returns a version 4 UUID.
Should I use UUIDs as database IDs?
They are fine when IDs must be unique across systems; for heavy write loads, time-ordered UUIDs (v7) index better than random v4.
How is a UUID formatted?
32 hexadecimal characters in groups of 8-4-4-4-12. The first character of the third group shows the version, which is 4 for v4.
Are UUIDs secure tokens?
Version 4 UUIDs from a secure generator are hard to guess, but for secrets such as password reset links, use a dedicated random token with enough length and an expiry.
What is a nil UUID?
00000000-0000-0000-0000-000000000000, sometimes used as an empty value.
How do I generate a UUID in Python?
import uuid, then uuid.uuid4().
Are UUIDs case-sensitive?
No. Uppercase and lowercase represent the same value, though lowercase is the usual form.