UUID Generator - Create Random v4 UUIDs

Click Generate to create one or more version 4 UUIDs. They're produced entirely in your browser using its cryptographically secure random generator — click any result to copy it, or copy them all at once.

What is a UUID?

A UUID (Universally Unique Identifier), sometimes called a GUID, is a 128-bit value written as 32 hexadecimal digits in the familiar 8-4-4-4-12 pattern, like f47ac10b-58cc-4372-a567-0e02b2c3d479. Its whole purpose is to let different systems generate identifiers independently and still be confident they'll never collide — no central authority or database lookup required.

Version 4 UUIDs (what this tool makes) are almost entirely random: 122 of the 128 bits are random, with a few fixed bits marking the version and variant. You can spot a v4 UUID because the 13th hex digit is always 4.

When and why you'd use it

Database keys — primary keys that can be created on the client or across shards without coordinating with a central counter.
Distributed systems — request IDs, message IDs, and trace IDs that stay unique across many servers.
Files and resources — unique filenames or object keys that won't clash.
Idempotency keys — safely retrying an API call without creating duplicates.

Worked examples

A generated v4 UUID: 3f2504e0-4f89-41d3-9a0c-0305e82c3301 — note the 4 starting the third group, marking version 4.

Need 50 IDs to seed a test database? Set the count to 50 and generate them all at once.

As a URL-safe identifier: /orders/9b2f... — UUIDs contain only hex digits and hyphens, so they need no escaping.

Frequently asked questions

Could two UUIDs ever be the same?

In practice, no. With 122 random bits there are about 5×10³⁶ possible v4 UUIDs. You would need to generate billions per second for many years before a single collision became even remotely likely.

What's the difference between v1 and v4?

Version 1 is based on the time and the machine's network address (so it can leak those). Version 4 is random, which is why it's the common default when you just need a unique, opaque ID.

Are these generated randomly and privately?

Yes. They're created locally with crypto.randomUUID(), which uses the browser's cryptographically secure random source. Nothing is sent to a server, and no list is stored.

Can I use a UUID as a database primary key?

Yes, and it's common. One trade-off: random v4 UUIDs aren't ordered, which can fragment some database indexes. If insert-order matters for performance, look at time-ordered schemes (like UUIDv7).

Unique, not secret. A UUID is unpredictable enough to be a good identifier, but it isn't a security token by itself — don't rely on "nobody can guess this URL" as your only access control. Use real authentication for anything sensitive.