Question 1

How do I use the UUID generator?

Accepted Answer

Pick a UUID version (v4 is the most common default), set the batch count and formatting options, and click Generate. For v3/v5, provide a name and choose a namespace UUID (or a custom namespace UUID). Copy individual rows or copy all lines at once.

Question 2

What is the difference between UUID versions?

Accepted Answer

v1 is time-based; v3/v5 derive from a namespace plus a name using MD5/SHA-1 respectively and are deterministic for the same inputs; v4 is random and is the typical choice for opaque identifiers.

Question 3

Which output formats are supported?

Accepted Answer

Standard hyphenated UUIDs, compact hex without hyphens, braces-wrapped strings, and a C-style grouped layout for quick copy into native code samples.

Question 4

What are namespace UUIDs (v3/v5)?

Accepted Answer

v3 and v5 generate stable UUIDs from a fixed namespace UUID plus a fixed name, useful when you need reproducible IDs across systems. v5 is generally preferred over v3.

Question 5

UUID vs GUID?

Accepted Answer

They usually refer to the same 128-bit identifier format. GUID is commonly used in Microsoft ecosystems.

Question 6

When should I use this tool?

Accepted Answer

Database keys, distributed tracing, session/request IDs, filenames, API testing payloads, and anywhere you need low-collision unique strings.

Online UUID and GUID Generator