UUID Generator — Random v4 UUIDs, One or a Hundred at a Time

Generate random UUID v4 identifiers one at a time or in bulk — up to 100 at once — with uppercase and hyphen options, all on your own device.

UNDERSTAND YOUR RESULTS

UUID Generator — Random v4 UUIDs, One or a Hundred at a Time guide

Generate random UUID v4 identifiers one at a time or in bulk — up to 100 at once — with uppercase and hyphen options, all on your own device.

How to use this tool

Choose how many UUIDs you need — from a single one to a batch of 100 — using the count box.
Set your format: UPPERCASE on or off, and hyphens on or off. Most databases and APIs expect the standard lowercase, hyphenated form, which is the default.
Click Generate UUIDs. A starter batch is already waiting when the page loads.
Click any single UUID to copy just that one, or use Copy all to take the whole batch, one per line — ready to paste into seed data, fixtures or a spreadsheet.

A worked example

A developer seeding a demo database needs 40 user IDs: set the count to 40, click Generate, then Copy all, and paste forty lines straight into the SQL seed file. Each one — for example 9b2f207e-6d3a-4b1f-8e5c-2a7d9c4f01b3 — is a valid version-4 UUID, generated fresh on that click.

How it works

Each UUID is built from 122 bits of randomness supplied by your browser’s cryptographic random source (crypto.randomUUID where available, otherwise crypto.getRandomValues with the version and variant bits set by hand, following RFC 4122 / RFC 9562). The randomness comes from the operating system’s entropy pool — the same source your browser uses for encryption keys — which is what makes collisions a practical impossibility rather than merely unlikely. Nothing is generated or stored on a server.

Frequently asked questions

What is a UUID v4?

A universally unique identifier, version 4, is a 128-bit value shown as 32 hexadecimal digits in five groups (8-4-4-4-12) where almost every bit is random. The fixed bits — a “4” starting the third group and an 8, 9, a or b starting the fourth — are how readers know it is version 4.

Can two generated UUIDs ever collide?

In practice, no. With 122 random bits, you would need to generate roughly a billion UUIDs per second for a century before a collision became likely. Systems like Git, Windows and every major database rely on exactly this property.

What is the difference between a UUID and a GUID?

Nothing of substance: GUID is Microsoft’s name for the same 128-bit identifier family. A UUID v4 from this page is a valid GUID anywhere GUIDs are accepted, including .NET and SQL Server (where it maps to the uniqueidentifier type).

Should I use uppercase or no hyphens?

Only when a specific system demands it. The canonical form — lowercase with hyphens — is what RFCs, documentation and most libraries display and accept. Stripping hyphens gives the “N” format some .NET and database contexts use; uppercase is mostly cosmetic.

Are these generated on a server and logged?

No. Generation happens in your browser from its built-in cryptographic random generator; the values are never transmitted, logged or stored anywhere. Refresh the page and they are gone unless you copied them.