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UUID v4 Generator

Random UUID v4 IDs in bulk — cryptographically random, ready to paste.

Processed locally – files never leave your device

A UUID v4 looks like 550e8400-e29b-41d4-a716-446655440000 — 32 hex digits in an 8-4-4-4-12 pattern, with a 4 marking the version.

Next: try Password Generator — Strong random passwords with custom rules.

Need a unique ID for a database row, an API request, a file name or a test fixture? This free UUID v4 generator creates random version-4 UUIDs in your browser — one at a time or in bulk — using your browser's cryptographic random number generator, not a predictable pseudo-random function.

Every ID follows the familiar 8-4-4-4-12 pattern, for example 550e8400-e29b-41d4-a716-446655440000. When you need structured test data around your new IDs, the JSON Formatter can tidy the payload, and a fresh Password Generator run covers the secrets that should never be a UUID.

How to use

  1. Choose how many UUIDs you need — 1, 5, 10 or 50.
  2. Click Generate UUIDs. A fresh set appears instantly.
  3. Use Copy all to copy every UUID, or Download .txt to save them as a file.
  4. Click Generate again any time for a completely new set.

Why use Toolsvine

Some ID generators run on a server or use Math.random, which is not random enough for identifiers that must never collide. Toolsvine uses crypto.getRandomValues, the same source of randomness your browser uses for security features — and because it runs locally, your IDs are never logged or sent anywhere.

What is a UUID v4?

A UUID (Universally Unique Identifier) is a 128-bit label written as 32 hexadecimal digits in five groups: 8-4-4-4-12, separated by hyphens. Version 4 means the ID is randomly generated: 122 of the 128 bits are random, while 6 bits are fixed — the version nibble is always 4, and the variant bits start with 10 in binary, so the first digit of the fourth group is always 8, 9, a or b.

How unique is “unique”?

With 122 random bits there are about 5.3 × 1036 possible version-4 UUIDs — roughly 3.4 × 1038 total, minus the fixed bits. You would need to generate around a billion UUIDs per second for about 85 years before the chance of a single collision reached 50%. In practice, collisions simply do not happen.

Reading a UUID

GroupDigitsMeaning
18Random
24Random
34First digit always 4 (version)
44First digit 8, 9, a or b (variant)
512Random

That fixed 4 in the third group is the quickest way to check a UUID really is version 4. Other versions exist — version 1 embeds a timestamp and a machine address, version 5 is derived from a name — but version 4 is the default choice when you just need a random, unguessable ID.

Frequently asked questions

Are these UUIDs really random?

Yes. They are built with crypto.getRandomValues, the browser's cryptographic random source. Math.random is never used, because it is predictable and not suitable for identifiers.

Can two UUIDs ever be the same?

In theory yes, in practice no. With 122 random bits the odds are so small that generating billions of IDs still leaves a collision effectively impossible — about a 50% chance only after a billion per second for 85 years.

How do I know a UUID is version 4?

Look at the first digit of the third group: it is always 4. The first digit of the fourth group is always 8, 9, a or b. Any UUID matching that pattern is a version-4 UUID.

Can I use a UUID as a password?

You could, but a dedicated password is better: UUIDs use only hex characters (16 symbols), while a password can draw on a much larger set. Use the Password Generator for secrets and keep UUIDs for identifiers.

Is anything I generate sent to a server?

No. Generation happens entirely in your browser. No UUID you create is uploaded, logged or stored anywhere.

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