GENERATORS

UUID Generator

Random v4 UUIDs from the browser’s cryptographic generator — plus v1, v6, v7, v5, NIL and MAX, an inspector, and export formats.

What this tool does

Generates every UUID version in active use, in bulk, with export formats ready to paste into code or a database, plus an inspector that takes any UUID apart to show exactly what it encodes.

Choosing a version

v4 — random — 122 bits of entropy from the browser's cryptographic random generator. The default choice for a plain unique ID with nothing else encoded in it.
v7 — Unix-time prefixed — starts with a millisecond timestamp, so IDs sort by creation time and stay index-friendly as a database primary key, unlike v4.
v6 — reordered time — the same time-based layout as v1, rearranged so it sorts lexically too.
v1 — Gregorian time + node — the original time-based UUID; note that it leaks its creation timestamp and generating node, so it is not the right choice anywhere that needs to stay private.
v5 — namespace + name — a SHA-1 hash of a namespace UUID and a name string, so the exact same input always produces the exact same UUID. DNS, URL, OID and X.500 standard namespaces are built in, or a custom namespace UUID can be used.
NIL and MAX — the reserved all-zero and all-one UUIDs defined by RFC 9562.

Bulk generation and formatting

Generate 1 to 500 at once. Formatting options apply to every UUID produced: uppercase, hyphens on or off, wrapping braces, and a urn:uuid: prefix. Copy the batch or download it in one of six formats — plain lines, a JSON array, CSV, a SQL VALUES list, C# Guid.Parse calls, or Python uuid.UUID literals.

Inspecting an existing UUID

Paste any UUID in and it is decoded field by field — version, variant, and for a time-based version (v1, v6, v7) the exact embedded timestamp and, for v1/v6, the generating node. A visual breakdown shows which hex digits correspond to which part of the 128-bit structure.

Privacy

Every UUID is generated and every inspection is decoded entirely in your browser, using the browser's own cryptographic random generator — nothing is sent to a server.

FAQ

Frequently asked questions

Is my data uploaded anywhere?

No. UUIDs are generated and inspected entirely in the browser -- nothing is sent to a server.

Which UUID version should I use for a database primary key?

v7 -- it starts with a millisecond timestamp, so rows stay sorted by creation order and index performance stays good, unlike a plain random v4 key.

How is v5 different from v4?

v4 is random every time. v5 hashes a namespace UUID together with a name string, so the same namespace and name always produce the exact same UUID -- useful when an ID needs to be reproducible from known input rather than random.

Can two v4 UUIDs ever collide?

In practice, no -- with 122 bits of random entropy, roughly 2.7 quintillion v4 UUIDs would need to be generated before there is even a 50% chance of a single collision.

Is a v1 UUID safe to expose publicly?

Not if the creation time or generating machine should stay private -- a v1 (and v6) UUID embeds both. Use v4 or v7 when that information should not be exposed.

What can the inspector tell me about a UUID I did not generate here?

Its version and variant always, and for a time-based version (v1, v6 or v7) the exact embedded creation timestamp -- plus the generating node for v1 and v6. A name-based UUID (v5 or v3) cannot be reversed back to its original namespace and name.