UUID / GUID Generator
Generate cryptographically random v4 UUIDs in bulk, in the format your system expects.
Where the randomness comes from
These UUIDs are built from crypto.getRandomValues(), the browser's cryptographically secure random source. That distinction is not academic. A v4 UUID generated from Math.random() — which a surprising number of snippets still do — draws from a fast, seeded, entirely predictable generator. Given a handful of outputs, the sequence can be reconstructed, and identifiers you assumed were unguessable become guessable.
If your UUIDs are only ever primary keys, that may not matter. If any of them appear in a URL that grants access to something — a password reset link, a shared document, an invite — it matters a great deal.
Format variants
Standard lowercase with hyphens is the canonical form and what you should store. Uppercase and braced {...} forms exist because Microsoft's GUID tooling emits them; strip to canonical before comparing, or you will get false mismatches between systems.
Common questions
Are these UUIDs cryptographically secure?
Yes. They use crypto.getRandomValues(), the browser's CSPRNG, not Math.random().
What is the collision risk?
Negligible for any realistic volume. A v4 UUID has 122 random bits; you would need to generate billions per second for decades before a collision became likely.
Why are there uppercase and braced formats?
Microsoft GUID tooling emits them. Normalise to canonical lowercase with hyphens before comparing values across systems.