UUID Generator
Runs in your browserRandom (v4), time-ordered (v7), time-based (v1), or hashed from a name so the same input always makes the same id (v5). Generate a batch, copy one or all of them.
Version
Fully random. The one most tools default to.
How this one works
v1, v4 and v7 all start as random bytes from crypto.getRandomValues. A v4 stamps two fixed bits (the version and the variant) over those bytes and leaves the rest untouched — 122 real bits of randomness. v1 and v7 both replace part of those bytes with the current time before stamping their own version, so ids created a moment apart sort the way they were created; the timestamp is readable back out of either (v1’s 100-nanosecond clock, or v7’s plain millisecond one), which a v4 never reveals. v1 also needs a node id, traditionally a network card’s MAC address — nothing here has one to give it honestly, so it uses random bytes instead, with the bit the spec sets aside for exactly that turned on.
v5 doesn’t touch the CSPRNG at all: it hashes a namespace and a name together with SHA-1 and keeps the first 16 bytes, so the same two inputs always produce the same id — useful for turning a URL or a DNS name into a stable identifier without a lookup table. The namespace can be any UUID, not only the four RFC 9562 predefines: an app minting ids for its own records can pick one UUID as its namespace once (a v4 works well) and hash every record’s name against it from then on. Version 3 is the same idea with MD5 in place of SHA-1; it’s not offered here because MD5 isn’t one of WebCrypto’s digest algorithms, and nothing else in this tool needs a hand-rolled hash function just for it.
Questions
Which version do I actually want?
v4 for almost everything — a general-purpose random id. v7 if it's a database primary key or a log id and you want inserts to stay roughly sorted. v5 if you need the same input to always produce the same id, such as turning a URL into a stable key. v1 mainly for compatibility with a system that already expects it; v7 does what v1 was for, better.
Are these valid RFC 9562 UUIDs?
Yes — the version nibble and the variant bits are set exactly as the spec requires, so anything that parses UUIDs will accept them and correctly report the version.
Is a v1 UUID safe to hand out publicly?
It reveals when it was created, to within a fraction of a millisecond, and if you generate several from the same tab in a row they share a random node id that ties them together as coming from one source — neither of those is true of a v4. If that matters, use v4.
Does this reach a server?
No. Every id — including a v5 name and namespace — is generated as JavaScript in this tab and never leaves it except when you copy one.