UUID v4 Generator

Generate random UUID v4 values (GUIDs) in bulk, up to 10,000 at once, using your browser's cryptographically secure random generator. Copy or download as text. UUID v4 is the most common UUID version, used for database keys, request IDs and test data.

About this tool

What is UUID v4?

A UUID v4 is a 128-bit identifier made almost entirely of random bits: 122 bits are random and the remaining 6 mark the version and variant. Because the space is so large, UUID v4 values can be created independently on any machine without coordination and without realistic risk of duplicates. Microsoft calls the same thing a GUID. This tool creates UUID v4 values with the uuid library, which uses the browser's cryptographically secure random number generator (Web Crypto).

How to use

  1. Enter how many UUIDs you need in Number of UUIDs (v4) (1 to 10,000).
  2. Click Generate. Click again for a new set.
  3. Use the buttons in the corner of the list to copy all UUIDs, download them as uuid4.txt, or view them full screen.

Features

  • 1 to 10,000 UUIDs per click, one per line
  • Lowercase, hyphenated 36-character format
  • Cryptographically secure randomness
  • Copy to clipboard or download as a text file
  • The last list is kept in this browser

How to recognize a UUID v4

xxxxxxxx-xxxx-4xxx-Yxxx-xxxxxxxxxxxx
  • The first character of the third block is always 4 (the version).
  • The first character of the fourth block is 8, 9, a or b (the RFC variant).
  • Every other hex digit is random.

Example: 3f2b8c1e-9a4d-4e7b-b6f0-2c5d8e1a9f30

How unlikely is a duplicate?

With 122 random bits there are about 5.3 × 10^36 possible values. You would need to generate roughly 2.7 × 10^18 UUIDs before the chance of a single collision reaches 50%. In practice, bugs such as a broken random generator are a far bigger risk than chance.

FAQ

Is a UUID the same as a GUID?

Yes. GUID (Globally Unique Identifier) is Microsoft's name for a UUID. A UUID v4 can be used wherever a random GUID is expected; some Windows tools simply display it in uppercase or inside braces.

Why are the UUIDs not in order?

UUID v4 is random by design, so it has no order. If you need IDs that sort by creation time (for example to keep database indexes compact), use UUID v7 or ULID.

Can I use a UUID v4 as a secret token?

The randomness is cryptographically secure, but UUIDs are usually treated as identifiers and end up in URLs and logs. For passwords, API keys or session secrets, use a dedicated token generator.

Are the UUIDs generated on a server?

No. Everything happens in your browser, and nothing is uploaded.

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