UUID Generator
Generate v1, v4, v5 or v7 identifiers in bulk — sortable, random, or name-based. Offline.
Your data is processed entirely in your browser and is never uploaded.
Tool workspace
$ uuidgen --version 7 --count 1000
Pick a version and a count, then Generate. v7 batches come out already sorted; v5 turns a name into the same id every time.
Not all UUIDs are random
Version 4 — Random
122 bits of cryptographic randomness. The default for opaque identifiers.
Version 7 — Time-ordered
A 48-bit Unix-ms prefix plus randomness. Sorts chronologically — ideal as a database key.
Version 1 — Time-based
Timestamp + clock sequence + node. Time-derived, but its bytes don't sort as strings.
Version 5 — Name-based (SHA-1)
A deterministic hash of a namespace + name. Same input always yields the same UUID.
Version 3 (name-based, MD5) is intentionally not offered: MD5 isn't available in Web Crypto, and a hand-rolled copy would risk silent corruption. v5 is its correct successor.
Quick answers
Which version should I use?
For an opaque id, v4. For a primary key you'll sort or insert in order, v7 — its time prefix keeps inserts sequential. For a stable id derived from a name (a URL, a DNS name), v5.
Are these generated on a server?
No. Every UUID is produced in your browser using the platform's cryptographic RNG (and SHA-1 for v5). Nothing you generate is transmitted or stored.
Why aren't v1 UUIDs sortable as strings?
v1 stores the low 32 bits of the timestamp first, so the string order doesn't follow time. That limitation is exactly what v7 was designed to fix — it puts the most-significant time bits at the front.
What does "deterministic" mean for v5?
The same namespace + name always hashes to the same UUID, on any machine. Generating a batch appends an index to the name so you get distinct ids; remove the index logic and you'd get the same id repeated.