Free, browser-based utilities for everyday developer workflows

Generate a UUID (v4)

Generate a random version-4 UUID — for primary keys, correlation IDs, or test fixtures — one at a time or in bulk, with secure browser randomness.

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The problem

You need a unique identifier: a database key, a request correlation id, or seed data for a test. A version-4 UUID is random and collision-resistant. Generating it in the browser gives you a valid UUID instantly without a library or a server call.

Sample input

Settings
version: 4 (random)
count:   1

Expected output

Example UUID
3f50b9a2-8c1e-4d7b-9f2a-1b6c5d4e3f21

Illustrative only — each run differs. The 13th hex digit is 4 (the version) and the 17th is 8-b (the variant); the 8-4-4-4-12 grouping is the standard UUID format.

How to do it

  1. Choose the UUID version, such as v4.
  2. Set how many to generate.
  3. Generate the UUIDs.
  4. Copy one or the whole list.
  5. Use them as keys, IDs, or test data.

Common mistakes

  • Expecting UUIDs to be sequential or sortable.
  • Using a v4 UUID where a time-ordered ID is wanted.
  • Storing a UUID as text when a native UUID type exists.
  • Assuming uppercase and lowercase forms are different IDs.
  • Trimming the dashes and breaking the standard format.

Related tools

Related guides

FAQ

What is a version-4 UUID?

A version-4 UUID is a 128-bit identifier whose bits are mostly random, formatted as 8-4-4-4-12 hex groups. It is the common choice for random unique IDs.

Are v4 UUIDs sortable?

No. They are random, so they do not sort by creation time. Use a time-ordered identifier if you need ordering.

How unique are they?

Collisions are astronomically unlikely for version 4 because of the large random space, so they are safe as keys without coordination.

Is uppercase or lowercase canonical?

UUIDs are case-insensitive; lowercase is the common canonical form. Treat the two cases as the same identifier.

Are the UUIDs uploaded?

No. Generation runs locally in your browser. Nothing is sent to a server.

UUIDs are generated locally in your browser. Nothing is uploaded.

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