UUID Generator
Generate random version-4 UUIDs in your browser, with options for case, hyphens, and quotes.
About the UUID Generator
The UUID Generator creates random version-4 UUIDs (also called GUIDs) instantly, right in your browser. A UUID is a 128-bit identifier that is, for all practical purposes, globally unique — you can generate one on your laptop, someone else can generate one on a server on the other side of the world, and the odds of the two colliding are so small they can be safely ignored. That property makes UUIDs the go-to choice for database primary keys, API request IDs, file names, session tokens, message identifiers, and anything else that needs a unique label without a central authority handing out numbers.
This tool produces UUIDs one at a time or in bulk, and every value is generated with your browser's built-in cryptographic random number generator (crypto.randomUUID). Nothing you generate is ever transmitted to a server, logged, or stored — it all happens on your device.
How to use
- A first batch of UUIDs appears automatically when the page loads.
- Set "How many" to the number of UUIDs you need, from 1 to 100.
- Toggle the formatting options to match what your project expects:
- Uppercase — outputs
A1B2C3…instead of the default lowercase. - Remove hyphens — produces a compact 32-character string with no dashes.
- Wrap in quotes — surrounds each value with double quotes, handy for pasting into code, JSON, or CSV.
- Uppercase — outputs
- Click Generate to produce a fresh batch with your chosen count and options.
- Click Copy all to copy every UUID to your clipboard, one per line, ready to paste anywhere.
The results appear in a read-only, monospaced list with one UUID per line, so they stay easy to read and copy.
What is a version-4 UUID?
A UUID (Universally Unique Identifier) is a 128-bit number, usually written as 32 hexadecimal digits split into five hyphen-separated groups: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. There are several "versions" that differ in how the bits are chosen. Version 4 is the random variant: almost all of its bits come from a random or pseudo-random source, with a small fixed pattern that marks it as v4. In the layout above, the 4 is constant (it identifies the version), and the y position is always one of 8, 9, a, or b (the variant bits). Everything else is random.
Because 122 of the 128 bits are random, the number of possible version-4 UUIDs is astronomically large — around 5.3 × 10³⁶. You would have to generate billions of UUIDs per second for many years before a collision became even remotely likely, which is why v4 is the most popular choice when you just need a unique value and don't want to coordinate with anyone. Unlike version-1 UUIDs, v4 contains no timestamp and no MAC address, so it doesn't leak information about when or where it was created.
Frequently asked questions
Are these UUIDs truly random?
Yes. They come from crypto.randomUUID, which is backed by your browser's cryptographically secure random number generator — the same class of randomness used for real security work, not the weak Math.random() found in many web toys. On the rare older browser without crypto.randomUUID, the tool falls back to building a valid v4 UUID from crypto.getRandomValues.
Is anything sent to a server or saved?
No. Every UUID is created entirely in your browser with JavaScript. Nothing is uploaded, logged, or stored — not even by us. Refresh the page and the current batch is gone, so copy what you need first.
Will two generated UUIDs ever be the same?
In practice, no. With about 5.3 × 10³⁶ possible values, the chance of a collision is negligible even across billions of generated IDs, which is exactly why v4 UUIDs are trusted as unique identifiers without any central registry.
What is the difference between a UUID and a GUID?
None that matters here. "GUID" (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier. A version-4 UUID and a v4 GUID are the same thing; the terms are interchangeable.
Can I generate UUIDs in bulk?
Yes. Set "How many" up to 100 and click Generate to produce a whole batch at once, then use Copy all to grab every value with one line per UUID.
Which formatting option should I use?
It depends on where the UUID is going. Lowercase with hyphens is the standard canonical form and works almost everywhere. Use Remove hyphens for compact keys or file names, Uppercase if a system expects it, and Wrap in quotes when pasting straight into code, JSON arrays, or spreadsheets.