Nothing you enter is sent anywhere — 100% on-device

UUID Generator (v4)

Cryptographically secure random UUIDs.

0 B uploaded — nothing you enter has been sent anywhere?

Nothing you enter and no file you choose is sent anywhere — everything runs inside this page, and no request carries your content to a server.

Other tools send what you type to a server and process it there. Even when they promise to erase it afterwards, your text sits on someone else’s machine in the meantime. Here there is no sending step at all. The more sensitive the content — passwords, contract wording, private notes — the more that difference matters. See how to verify it →

Generate identifiers that will never collide, as many as you need at once

Database records, uploaded file names and request trace IDs all need values that must never repeat. This tool creates random version 4 UUIDs, from one up to 1,000 at a time, and can output them in uppercase or without hyphens. They are generated on your device and not recorded anywhere.

A closer look

A UUID is 32 hexadecimal digits split into groups of 8-4-4-4-12, 36 characters in total. Version 4 fills 122 of its 128 bits with random data; the remaining 6 bits mark the version and variant. That leaves about 5.3 × 10^36 possible values, so separate servers can mint IDs without talking to each other and the chance of a clash is negligible in practice. You can recognize a v4 value at a glance: the third group always starts with 4, and the fourth group starts with 8, 9, a or b.

Values come from crypto.randomUUID(), which is built into the browser and draws on a cryptographically secure random source, unlike IDs improvised with Math.random(), whose next value can be guessed. The page generates five UUIDs as soon as it opens. The Count box accepts 1 to 1,000: a larger number is capped at 1,000, and 0 or an empty box gives you one. The UUID standard recommends lowercase output and case-insensitive comparison, so only turn on Uppercase when the receiving system insists on it.

How to use it

When it helps

Primary keysSeveral apps or servers can create records independently without key collisions, and unlike 1, 2, 3 the keys reveal nothing about how many records exist or what comes next.
Seeding test dataGenerate 1,000 at once and paste them into a spreadsheet column to fill the ID field of sample users or orders.
Upload file namesSaving user photos under UUID names avoids overwriting files that share a name and keeps the original file names private.
Windows-style GUIDsRegistry entries and some .NET settings expect uppercase GUIDs; generate with Uppercase on and add the curly braces yourself.

Common snags

I ticked an option but the list did not change.Options apply to the next run. Press Generate again, and note that this produces brand-new UUIDs rather than reformatting the old ones. To uppercase values you already use, change the case in a text editor instead.
I need more than 1,000.One run is capped at 1,000. Generate and copy several times and join the lists; each run draws fresh random values, so the batches will not overlap.
I need UUIDs that sort by creation time.This tool only makes version 4. Time-ordered version 7 and version 1 are not offered, so for keys that should land in index order, use the generator in your database or UUID library.
The output box is empty.Very old browsers do not have crypto.randomUUID(), so nothing can be generated. Update Chrome, Edge, Safari or Firefox and reload the page.

Tip Pick one storage format, lowercase with or without hyphens, and stick to it, so the same UUID is never compared as two different strings and missed in a lookup.

Notes

Is it secure?

Yes — it uses the browser's built-in crypto.randomUUID(), a cryptographically secure random source, and generated values never leave your device.