Question 1

What is a UUID?

Accepted Answer

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value used to identify something uniquely without any central authority. Written as 32 hexadecimal digits in five hyphen-separated groups (8-4-4-4-12), it is unique enough that two independently generated UUIDs will, in practice, never collide.

Question 2

Which UUID version should I use?

Accepted Answer

Use v4 (random) for general-purpose unique IDs — it is the most common. Use v7 for database keys that should sort by creation time (it embeds a millisecond timestamp). Use v5 (or v3) when you need a deterministic UUID derived from a namespace and a name — the same inputs always produce the same UUID. v1 is the classic time-based UUID; this tool generates it with a privacy-safe random node.

Question 3

Are these UUIDs cryptographically secure?

Accepted Answer

The random parts of v4, v1, and v7 come from the Web Crypto API — the same secure source as the browser's built-in crypto.randomUUID(). This tool never uses Math.random(). Note that a UUID is an identifier, not a secret: v4 is unguessable, but you should not use any UUID as a password or security token.

Question 4

What is UUID v7 and why is it useful?

Accepted Answer

UUID v7 (RFC 9562) starts with a 48-bit Unix-millisecond timestamp followed by random bits. Because the timestamp comes first, v7 UUIDs sort in creation order, which makes them far better than v4 as database primary keys — inserts stay sequential and indexes stay compact.

Question 5

How does the validator work?

Accepted Answer

Paste any UUID into Validate mode and the tool checks the 8-4-4-4-12 format, then reads the version and variant bits directly from the value. For time-based v1 and v7 it also reconstructs the timestamp embedded in the UUID and shows it in ISO format. It recognises the special Nil and Max UUIDs too.

Question 6

Is my data sent to a server?

Accepted Answer

No. All generation and validation happens entirely in your browser. The UUIDs, any names you enter for v3/v5, and any UUID you validate never leave your device — there is no upload, no logging, and no account.

UUID Generator

How this works & your privacy

Limitations

Standards & references

Frequently Asked Questions

UUID Generator

How this works & your privacy

Limitations

Standards & references

Frequently Asked Questions