UUID Generator
Generate cryptographically secure UUID v4 identifiers — one at a time or 100 in bulk.
About this tool
A UUID (universally unique identifier, called a GUID in the Microsoft world) is a 128-bit value like 550e8400-e29b-41d4-a716-446655440000 — designed so that anyone can generate one anywhere, with no central authority, and be effectively certain it has never existed before. That property makes UUIDs the standard choice for database primary keys, API request IDs, session tokens, file names and distributed systems where two machines must create IDs without coordinating.
This generator produces version 4 UUIDs — the fully random variant, and the one you want in almost every case — using crypto.randomUUID, the browser's cryptographically secure generator. That's not a cosmetic detail: UUIDs built on weak randomness can collide or be predicted, which matters when an ID doubles as an unguessable reference.
One is generated the moment the page loads. Need more? Set a count up to 100 and generate the batch — each with its own copy button, plus Copy All to grab the whole newline-separated list for pasting into a spreadsheet, seed script or test fixture. The chance of any two v4 UUIDs colliding is so small (about 1 in 5.3 undecillion) that the practical answer to "could these repeat?" is simply no.
How to use the UUID Generator
- 1A UUID is ready the moment the page loads — click Copy next to it.
- 2For a batch, set how many you need (up to 100) and click Generate.
- 3Copy individual UUIDs, or Copy All for the whole list.
- 4Click Generate again anytime for a completely fresh set.
Frequently asked questions
What's the difference between UUID and GUID?
Nothing meaningful — GUID (globally unique identifier) is Microsoft's name for the same 128-bit standard. A GUID field in a .NET or SQL Server system accepts exactly what this tool generates.
Can two generated UUIDs ever be the same?
Theoretically yes, practically no. A v4 UUID has 122 random bits; you'd need to generate about a billion UUIDs per second for roughly 85 years to reach a 50% chance of a single collision. Systems worldwide treat them as unique without checking.
What is version 4, and are there other versions?
v4 is fully random and is the right default for IDs. Other versions exist — v1 embeds a timestamp and MAC address (a privacy leak), v5 is derived from a name via hashing, and newer v7 is time-ordered for database index locality. When in doubt, v4.
Are these UUIDs generated securely?
Yes — via crypto.randomUUID, the browser's cryptographically secure source, entirely on your device. They're never transmitted, logged or stored, so they're safe to use as tokens and keys.