UUID / GUID Generator (v1, v3, v4, v5 & v7)

Q: What's the difference between UUID v1, v3, v4, v5, and v7?

v1 and v7 embed a timestamp (v1 also adds a node/MAC-derived identifier; v7 sorts naturally as a database key). v4 is fully random. v3 and v5 are deterministic: they hash a namespace UUID plus a name (e.g. a domain or URL) with MD5 (v3) or SHA-1 (v5) so the same input always produces the same UUID.

Q: Why would I want a deterministic UUID (v3/v5)?

When you need a stable, collision-resistant ID derived from an existing identifier — like turning a URL, email, or hostname into a UUID — without maintaining a separate lookup table. Running the same namespace + name through this tool again always reproduces the same UUID.

Q: Which namespace should I use for v3/v5?

Use the standard DNS namespace when your name is a domain name, URL namespace when it's a full URL, or your own custom namespace UUID (generate one with v4 once, then reuse it) when you want IDs scoped to your own application or dataset.

Q: Is my data sent to a server?

No. All UUID generation, including the MD5/SHA-1 hashing for v3/v5, runs locally in your browser via the widely-used `uuid` npm package — nothing is uploaded.

Your version 4 UUID (GUID)

UUID (universally unique identifier) and GUID (globally unique identifier) are commonly used interchangeably. This tool generates RFC-compatible version 1, 3, 4, 5, and 7 UUIDs that can be used anywhere a GUID string is expected. (Note: some Microsoft APIs serialize a GUID's bytes in a different order, so the two aren't always byte-for-byte identical in binary form.)

UUID v7 adds a Unix timestamp prefix, so newer IDs sort after older ones and work well as database primary keys or append-friendly indexes. UUID v1 also embeds a timestamp, plus a node identifier (a random 48-bit value here, since no MAC address is available in the browser) and a clock sequence. Choose v4 when you want a fully random UUID with no embedded ordering information.

UUID v3 and v5 are deterministic: the same namespace + name always produces the same UUID, which makes them useful for generating stable IDs from existing identifiers (e.g. hashing a URL or domain name into a UUID) without a lookup table. v3 uses MD5 and v5 uses SHA-1 — v5 is generally preferred today since MD5 and SHA-1 are both considered weak for cryptographic purposes, though that weakness doesn't meaningfully matter for this non-security identifier use case.

UUID / GUID Generator (v1, v3, v4, v5 & v7)

Your version 4 UUID (GUID)

FAQ

What's the difference between UUID v1, v3, v4, v5, and v7?

Why would I want a deterministic UUID (v3/v5)?

Which namespace should I use for v3/v5?

Is my data sent to a server?

See also