UUID Generator
Generate UUID v4 identifiers instantly in your browser.
56f45528-491b-4b5b-97cc-fd994fdb191aWhen a UUID generator is the right tool
A UUID is a 128-bit identifier written as five hyphenated hex groups. Version 4 is the common random form: useful as a primary key, a request id, or a filename that should not collide with others. A generator is for that moment. You choose how many you need, click Generate, and copy the list.
This page only creates UUID v4, using crypto.randomUUID() in your browser. It does not create time-based or name-based UUIDs. If you want a sortable identifier, try the ULID Generator. If you want a shorter random string, try the Nano ID Generator.
Use cases
Minting one id for a record or a filename
The page loads with a single lowercase UUID already generated. Copy All (or select that one line) when you need an id right away. Click Generate if you want a different value.
Making a batch for a fixture or a seed script
Set the quantity to any number from 1 to 100, then choose Generate. The list is replaced with that many new IDs. Copy All puts them on the clipboard, one per line, ready to paste into a file. Changing the quantity field alone does not refresh the list.
Matching a style that expects uppercase hex
Some systems document UUIDs with uppercase A–F. Turn on Uppercase to convert the IDs already on the screen; Generate will then follow that choice for new ones. The hyphens are always kept.
How generation works
Each Generate click calls crypto.randomUUID() once per requested id, then optionally uppercases the result. The output is the standard 8-4-4-4-12 hex form. In a version 4 UUID the first digit of the third group is 4, and the first digit of the fourth group is 8, 9, a, or b (or the uppercase equivalents). The page does not strip variant or version bits; it shows whatever the browser produced.
Uppercase can also be toggled without generating, in which case the existing list is only re-cased. Copy All joins the visible list with newlines.
a1b2c3d4-e5f6-41a2-b3c4-d5e6f7a8b9c0
Version 4 (random), lowercase, with hyphens.
The third group starts with 4, which marks the version.
The fourth group starts with 8, 9, a, or b, which marks
the RFC 4122 variant.Your generated values will be different, but they should follow this layout. If a consumer rejects the id, check whether it expected a different version, a string without hyphens, or uppercase letters — this page can only change the case, not the version or the hyphens.
What this tool does not do
It does not generate UUID v1, v5, or v7, ULIDs, or Nano IDs. It does not remove hyphens, validate an existing UUID, or guarantee uniqueness beyond what the browser's random generator provides. Nothing is sent to a server. A non-secure context or a very old browser may not implement randomUUID.
How to use UUID Generator
- Set the quantity (1 to 100) if you need more than one id.
- Turn on Uppercase if you want letters A–F in uppercase.
- Choose Generate to build a new list. The first id is already created when the page loads.
- Choose Copy All to copy the list, one UUID per line.
Frequently asked questions
Which UUID version does this page generate?
UUID version 4 only, via the browser’s crypto.randomUUID() function. These are random identifiers. There is no option for version 1 (time-based), version 5 (name-based), or version 7 (time-ordered). If you need a sortable ID, try the ULID or Nano ID generators instead.
How many UUIDs can I generate at once?
Between 1 and 100. The quantity field is clamped to that range. Changing the number does not generate new IDs by itself; choose Generate to build a new list of that length. The page starts with a single lowercase UUID already filled in.
What does the Uppercase option change?
It changes the letters A–F between lowercase and uppercase on the IDs already on the screen, without generating new ones. Generate then produces new IDs in the case you have selected. The hyphens stay in place; there is no option to strip them.
How does Copy All work?
It copies every UUID in the list, one per line, in the case currently shown. There is no per-row copy button; you can also select a single line on the page if you only need one.
Are these UUIDs unique and safe to use as identifiers?
Version 4 UUIDs have a very large random space, which is why they are widely used as identifiers. This page does not talk to a server or keep a log of what it generated. Uniqueness still depends on the browser’s cryptographic random generator. Do not treat a UUID as a secret or as a proof of identity.
Is anything sent to a server?
No. Generation runs in your browser. Closing the tab discards the list unless you have copied it.
What if crypto.randomUUID is not available?
The button uses that standard Web Crypto method, which modern browsers provide on secure (HTTPS) pages. An older browser or a non-secure context may fail to generate IDs. There is no fallback generator in the page.
Related tools and guides
References
- RFC 4122 defines the UUID layout used here, including version 4 (random) and the variant bits. A later revision, RFC 9562, also describes version 7, which this page does not generate.
- crypto.randomUUID() is the Web Crypto method that produces each identifier.