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Tool 5.11

UUID generator: v4 and v7 GUIDs in bulk

Generate random UUID v4 or time-ordered UUID v7 (RFC 9562) in your browser, 1 to 1000 at a time, in uppercase or without dashes. Copy or download.

Runs on your deviceRuns entirely in your browser: nothing you type or upload leaves your device.

How to use it

  1. Choose v4 (random) or v7 (time-ordered).
  2. Set how many you need (1 to 1000) and the format.
  3. Press Generate, then copy them all or download a .txt file.

IDs you can create anywhere without asking

A UUID (also called GUID) is a 128-bit identifier written as 32 hexadecimal characters in five groups. Its point is that any computer can create one on its own, with no central counter, and it won't clash with the ones created elsewhere. That's why they're used as database keys, order and request numbers in APIs, file names for uploads and test data.

Programs usually generate them in code. This page is for the other times: filling a spreadsheet or a test database by hand, creating a key for a configuration file, or checking what a valid UUID looks like.

Reading a UUID: v4 and v7 side by side

A v4 looks like f601b782-da4a-4ffb-aa9d-c076a7f56f5d. The first character of the third group is the version, 4, and the first of the fourth group is always 8, 9, a or b. Everything else is random.

Switch to v7 and generate a few. You'll get values like 01a0d3d2-c240-70de-b18e-f7bf24f7a437 and 01a0d3d2-c240-70df-831e-3448309b556e. The first 12 characters, 01a0d3d2c240, are the creation time in milliseconds, here 24 September 2026 at 14:30 UTC. Both were made in the same millisecond, so the counter right after the 7 goes from 0de to 0df, and sorting them as text puts them in creation order.

Not a secret, and not always in order

Don't use a UUID as a secret, such as a password-reset link or an access token. The RFC that defines them says not to assume they are hard to guess, and a v7 openly shows when it was created. Use a random token made for that purpose.

Keep the standard form, lowercase with dashes, unless a system asks for something else: the No dashes and Uppercase options are for systems that need them, and some programs reject them. Also note that the time order of v7 only helps when the database compares UUIDs as text or bytes from left to right; SQL Server's uniqueidentifier type, for example, sorts by the last group first.

FAQ

UUID v4 or v7?

A v7 starts with a timestamp, so new IDs sort after older ones, which keeps database indexes fast. A v4 is fully random and reveals nothing. Use v7 for database keys and v4 when the creation time shouldn't be visible.

Can two UUIDs collide?

In practice, no. A v4 has 122 random bits; you would have to generate billions per second for many years before a collision became likely.

Are these UUIDs generated securely?

Yes. They come from the browser's cryptographic random generator on your device and are never sent anywhere.

Is a GUID the same as a UUID?

Yes. GUID is the name Microsoft uses for the same 128-bit identifier, with the same 8-4-4-4-12 format. Some Microsoft tools show them in capitals or between braces, like {F601B782-…}, but the value is the same.

Can I use these as the folio fiscal of a Mexican invoice?

No. The folio fiscal of a CFDI is a UUID, but it is assigned by the authorised certification provider (PAC) when the invoice is stamped. A UUID generated here has the right format but belongs to no invoice. To check a real folio, use the SAT's CFDI verification service.

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