UUID Generator

Built & maintained by the MatrixInn Solutions engineering team · Last reviewed June 2026

How to generate a UUID online

Enter how many UUIDs you need (1 to 100) in the box above.
Click Generate — random version-4 UUIDs appear instantly, one per line.
Click Copy all to grab the whole list, or select individual lines you need.

The list refreshes the moment you click Generate, so you can dial the count up or down and regenerate as many times as you like with no waiting and no rate limit. Each batch is produced fresh, so nothing carries over between runs — use Clear to empty the box when you are done.

Why use a UUID generator?

UUIDs (also called GUIDs) give you globally unique identifiers without a central authority or database round-trip, which makes them ideal for primary keys, API tokens, file names, event IDs, and distributed systems where two machines must mint IDs independently without colliding. A version-4 UUID is built from 122 random bits, so each value is effectively impossible to guess or duplicate. This generator uses your browser's cryptographically secure random source, producing standards-compliant identifiers in milliseconds — and because it runs entirely client-side, none of your generated IDs are ever logged or transmitted.

Anatomy of a version-4 UUID

Every UUID is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx — that is 8-4-4-4-12 characters. Two positions are not random. The M digit always holds the version (a literal 4 for v4), and the top bits of the N digit hold the variant, which for standard UUIDs makes that digit one of 8, 9, a, or b. The remaining 122 bits are random. Knowing this lets you eyeball whether a string is a valid v4 UUID at a glance.

UUID versions compared

v4 is the everyday default, but it is not the only version. The table below shows when each common variant fits.

Version	Based on	Sortable?	Best for
v1	Timestamp + MAC address	Roughly	Legacy systems; leaks host and time
v4	Random bits	No	General-purpose IDs, tokens, keys
v5	Namespace + SHA-1 hash	No	Deterministic IDs from a known name
v7	Unix timestamp + random	Yes	Database keys needing index locality

How unique are version-4 UUIDs really?

With 122 random bits, a v4 UUID has about 5.3 × 10³⁶ possible values — roughly five undecillion. To put that in perspective, you would need to generate a billion UUIDs per second for about 85 years before the probability of a single accidental collision even reached 50%. For any realistic application — even one minting millions of IDs a day — the chance of two values clashing is so small it is treated as zero in practice, which is exactly why UUIDs let independent services create keys without coordinating. The one caveat is the quality of the randomness behind them: a weak or seeded pseudo-random source narrows the real space and reintroduces collision risk. This generator avoids that pitfall by drawing from the browser's crypto.getRandomValues() CSPRNG rather than Math.random(), so every batch you produce here is backed by cryptographically strong entropy.

Common use cases

Database keys — assign IDs on the client or app server before an insert, so you never wait for an auto-increment value.
Idempotency keys — tag an API request with a UUID so retries are de-duplicated safely.
Correlation IDs — stamp a request with a UUID and trace it across logs, queues, and microservices.
File and object names — generate collision-free upload names without checking what already exists.
Test fixtures — seed fake records, sessions, or device IDs while developing and writing tests.

Tips & gotchas

UUIDs are identifiers, not secrets — they are unguessable in practice but should never stand in for a password or auth token.
Store them as a 16-byte binary type when your database supports it; the 36-character text form wastes space and index room.
Random v4 keys can fragment indexes on high-volume tables — reach for v7 or another time-ordered scheme if insert throughput matters.
Case and hyphens are cosmetic — UUIDs are case-insensitive, so normalize to lowercase to keep comparisons and lookups consistent.

Frequently asked questions

Is this UUID generator free and private?

Yes — it is 100% free with no sign-up, and completely private. UUIDs are generated in your browser using the native crypto API; nothing is sent to or stored on any server.

What is a version-4 UUID?

A UUID v4 is a 128-bit identifier whose bits are almost entirely random (with a few fixed version and variant bits). It looks like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx and is the most common type for keys, tokens, and IDs.

Is a UUID the same as a GUID?

Effectively yes. GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit standard. The format and uniqueness guarantees are identical, so a v4 UUID can be used anywhere a GUID is expected.

Are these UUIDs really unique?

For practical purposes, yes. A v4 UUID has 122 random bits, so the chance of generating the same one twice is astronomically small — you would need to create billions of them before a collision became remotely likely.

Can I use a v4 UUID as a database primary key?

You can, and many systems do. The trade-off is that fully random UUIDs are not sequential, which can fragment B-tree indexes and hurt insert performance at scale. If that matters, consider a time-ordered variant like UUID v7, or store the value as a 16-byte binary type rather than a 36-character string.

Is UUID v4 cryptographically secure or just random?

The randomness comes from your browser's cryptographically secure generator, but a UUID is an identifier, not a secret. Treat it as unguessable for practical purposes, yet never rely on a UUID alone as a password, session token, or access key.