UUID v4 Generator

Create cryptographically random UUID version 4 identifiers.

freeworks offlinenothing uploaded
Input
Output
—

About uuid v4 generator

UUID v4 Generator does its work in front of you rather than sending anything away to be processed. What you see is the whole of it.

Everything runs client side, which is the only arrangement where a privacy claim is checkable. Open the network tab and watch it stay empty.

You will find it under IDs & generators, alongside 13 other tools for the same sort of job.

Uses Web Crypto API for secure randomness with optional uppercase output and batch generation up to 100.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Single UUID v4
Generate one random UUID v4
Input
count: 1
uppercase: false
Output
c0e5bab7-a47c-46a6-b727-f04326611ae7
Uppercase UUID v4
Generate 3 uppercase UUID v4 identifiers
Input
count: 3
uppercase: true
Output
61820CC8-299B-495A-B2F6-444A2CE393B6
CB3C3FC9-DC5E-4951-B0F4-3842A2304FC4
67E95FF5-10A2-48E9-8B63-F0F8D5C427E3

Questions

Does UUID v4 Generator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use UUID v4 Generator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.