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Developer & Data

UUID Generator

Generate one or many RFC-compatible UUID v4 values using your browser's secure random number generator.

UUID version: v4 (random) — generated with your browser’s cryptographically secure random number generator, never a predictable or sequential pattern.

Result

Generated locally in your browser — nothing is sent anywhere.

Set a quantity and click Generate — clicking it again produces a fresh batch each time. Each value is a standard UUID v4 (random), e.g. 3fa85f64-5717-4562-b3fc-2c963f66afa6, suitable for database keys, test data, or any place you need a unique identifier.

This tool generates version 4 (random) UUIDs only — it does not produce v1 (time-based), v3/v5 (name-based/hashed), or v7 (time-ordered) variants.

What is inside a version 4 UUID

A UUID is 128 bits written as 32 hexadecimal digits in groups of 8-4-4-4-12. In version 4, six bits are fixed: the first digit of the third group is always 4 (the version), and the first digit of the fourth group is 8, 9, a or b (the variant). The other 122 bits come from your browser's cryptographically secure random number generator.

Collisions are possible but vanishingly unlikely. With 122 random bits, the chance that any two of a billion UUIDs match is about 1 in 10 quintillion (9.4 × 10⁻²⁰). You would need around 2.7 × 10¹⁸ UUIDs, a billion a second for roughly 86 years, before a duplicate became as likely as not.

How to use the UUID Generator

  1. Enter how many UUIDs you need in the Quantity (max 100) field.
  2. Click Generate to create a new batch.
  3. Click Copy next to a single UUID, or Copy all to copy the whole list.
  4. Click Generate again whenever you need a fresh set.

Example: Three IDs for test records

Set Quantity to 3 and click Generate. You get three lowercase v4 UUIDs, for example 839b2cc7-0af7-47b5-9d75-fc61eceb1c63, 8c76b48f-28d5-4ee8-a397-0644de86c7c7 and 3c66e3d0-c24d-44e5-a555-8465adedfaf7 (yours will differ, since they are random). Copy all puts them on the clipboard one per line.

Questions about the UUID Generator

What happens if I ask for more than 100?
The quantity is clamped when you click Generate: anything above 100 becomes 100, and zero or an empty value becomes 1.
How can I tell a value is version 4?
The first character of the third group is always 4, and the first character of the fourth group is 8, 9, a, or b, which marks the RFC 4122 variant.
Are the UUIDs uppercase or lowercase?
Lowercase hexadecimal with hyphens. If a system needs uppercase, convert them afterward; UUID comparison is normally case-insensitive.
Is a UUID shown before I click anything?
Yes, one UUID is generated when the page loads, so you can copy it right away.
Can two UUIDs ever be the same?
In principle yes, in practice almost never. Version 4 UUIDs have 122 random bits: the chance of any duplicate among a billion of them is about 9.4 × 10⁻²⁰.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier format, and a version 4 GUID is a random UUID like the ones generated here.