UUID Generator

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 36 characters like f47ac10b-58cc-4372-a567-0e02b2c3d479. It's designed to be unique across space and time without a central authority, so different systems can generate IDs independently and practically never collide. This tool generates version 4 UUIDs — the random kind — using your browser's cryptographic random source.

Where they're used

• Primary keys in databases (no coordination needed between servers).
• Request/trace IDs, session tokens, file names, idempotency keys.
• Anywhere you need a unique ID generated on the client or offline.

FAQ

Could two UUIDs ever be the same?

In theory yes, but a v4 UUID has 122 random bits — you'd need to generate billions per second for many years before a collision became likely. For all practical purposes they're unique.

What version of UUID does this generate?

Version 4, the random kind, which fills 122 bits with random data. It's the most common choice when you just need a unique identifier and don't need it sortable by time, unlike version 1 (timestamp-based) or version 7.

Are the UUIDs cryptographically random?

Yes. They're generated using your browser's built-in cryptographic random source rather than a weak pseudo-random function, which makes them suitable for tokens and keys where unpredictability matters.

Should I use a UUID as a database primary key?

You can, and it lets multiple servers generate keys without coordinating. The trade-off is that random v4 UUIDs are larger and less index-friendly than sequential integers, so for very high-write tables some teams prefer a time-ordered ID like UUID v7.

Is this generator free, and is it private?

Yes, it is completely free with no sign-up, and every UUID is generated locally in your browser, so nothing is sent to a server. It works on phones, tablets, and desktops.