v1 = time + node, v4 = random, v7 = time-ordered random (sortable, recommended for new IDs).
About UUID Generator
UUID Generator produces universally unique identifiers in the standard formats: v4 (random, the default in most modern systems), v1 (timestamp + node-id), and v7 (timestamp-prefixed random, sortable by creation time). Generate a single UUID with one click or a bulk batch when you need many at once. The output is a 36-character canonical string with hyphens — `xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx`.
Reach for it whenever you need a stable, collision-resistant identifier without coordinating with a central authority: primary keys for distributed systems, request-correlation IDs in logs, file names that must not collide, idempotency tokens for retried API calls, or test fixtures that need to differ between runs. Pick v4 unless you have a reason to prefer otherwise; v7 is worth choosing when the IDs are stored in a database whose B-tree index benefits from chronological insert order. v1 leaks the generating machine's MAC address by spec — useful for forensics, undesirable for privacy.
Examples
(click Generate, version v4)550e8400-e29b-41d4-a716-446655440000v4 random UUID. The third group's first hex digit (`4` here) marks the version; the fourth group's first hex digit (`8`–`b`) is the variant.
Frequently asked questions
Which UUID version should I use?
v4 for almost everything — fully random, no privacy implications. v7 is a strong choice when the IDs go into a database index and you want chronological clustering for cache locality. v1 is rarely the right answer in modern systems because it embeds the generating machine's MAC address.
How likely is a collision?
Vanishingly. The probability of generating two identical v4 UUIDs across one trillion IDs is around 50%. For practical workloads — billions of IDs — collisions are not a real concern; bigger risks are bugs in your generator or copy-paste mistakes.
Are these UUIDs cryptographically random?
Yes. The browser's `crypto.getRandomValues` is used as the entropy source for v4 and v7, so the output is suitable for security-sensitive contexts (session tokens, idempotency keys, single-use API tokens when you have nothing better).
Can I generate a deterministic UUID from a name?
v3 (MD5-based) and v5 (SHA-1-based) UUIDs derive a UUID from a namespace UUID plus a name string, so the same input always produces the same UUID. They are useful for content-addressed identifiers but are not in this tool's quick-generate set; they are rarely needed in everyday work.