How to generate UUIDs in bulk
- Ten UUIDs are ready as soon as the page loads. To get a different number, set How many (1 to 1000) and press Generate.
- Pick a format: Uppercase, No hyphens for 32 bare hex digits, or Braces for the {…} style used by Windows and .NET. The options re-format the current batch without generating new values.
- Click Copy all, or Download .txt to save them as uuids.txt, one per line.
Why use this tool
Primary keys and test data
Seed a database, write test fixtures or mock API responses with realistic IDs without opening a terminal. UUIDs can be created anywhere without a central counter, which is why distributed systems use them as keys.
Idempotency and correlation keys
Payment and other APIs, Stripe among them, accept an idempotency key so that a retried request is only processed once, and Stripe suggests a v4 UUID for it. The same kind of value works as a correlation ID for tracing one request through your logs.
GUIDs for Windows and .NET
Visual Studio project files, COM class IDs and registry entries use GUIDs, usually written in uppercase inside braces. Tick Uppercase and Braces to get that format directly.
Collision-free names
Name uploaded files, temporary folders, cache entries or cloud resources with a UUID and they will not clash, even when several machines create them at the same moment.
Private by design
Each UUID is created on your device by your browser’s cryptographically secure random generator. Nothing is fetched from a server, and the values you generate are never sent or stored anywhere.
Good to know
What makes it version 4. A UUID is 128 bits. In version 4, 122 of them are random and 6 are fixed: the 13th hex digit is always 4 (the version) and the 17th is 8, 9, a or b (the variant). Every value here therefore matches xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is one of those four digits.
Where the randomness comes from. Values come from your browser's cryptographically secure generator, through crypto.randomUUID(). On browsers that lack it, crypto.getRandomValues() is used and the version bits are set by hand. Math.random() is never used, and nothing is fetched from a server.
Collisions. 122 random bits allow 2¹²² values, about 5.3 undecillion. You would need to generate around 2.7 quintillion (2.7 billion billion) UUIDs before the chance of even one duplicate reached 50%.
Two cautions.
- RFC 9562 warns not to assume UUIDs are hard to guess. Use them as identifiers, not as passwords or secret access tokens.
- Version 4 values are not ordered by time. For large tables with B-tree primary keys, random keys spread inserts across the index; UUID version 7, which starts with a timestamp, avoids that. This tool generates version 4 only.
In — How many: 3, default format
3Out — Three v4 UUIDs
bf597094-5649-4bf4-8ce9-104c3fec4bd6
0ae23bba-f3c5-4d14-abf5-7fe9047b9d2f
e8d8841b-6aaf-481e-9d42-3649d190e9fd| Options | Output | Typical use |
|---|---|---|
| None (default) | bf597094-5649-4bf4-8ce9-104c3fec4bd6 | Canonical form; most databases |
| Uppercase | BF597094-5649-4BF4-8CE9-104C3FEC4BD6 | GUIDs shown in capitals |
| No hyphens | bf59709456494bf48ce9104c3fec4bd6 | Compact keys, file names |
| Uppercase + Braces | {BF597094-5649-4BF4-8CE9-104C3FEC4BD6} | Registry, COM, .NET |
Frequently asked questions
Is a UUID the same as a GUID?
In practice, yes. GUID (globally unique identifier) is Microsoft’s name for the same 128-bit format. Microsoft tools usually show GUIDs in uppercase and often in braces, which you can match with the Uppercase and Braces options.
Can two generated UUIDs ever be the same?
In theory, yes; in practice, no. With 122 random bits you would need to generate about 2.7 quintillion (2.7 billion billion) UUIDs before the chance of a single duplicate reached one in two.
Are these UUIDs safe to use in production?
Yes. They come from the same secure random generator that browser cryptography uses, and they are standard version 4 values. They are created on your device and are never sent or stored anywhere.
What is the difference between UUID v4 and v7?
Version 4 is fully random apart from the version and variant bits. Version 7, defined in RFC 9562 (2024), starts with a 48-bit Unix timestamp in milliseconds, so values sort by creation time and keep database index inserts in order. This page generates version 4.
Are UUIDs case-sensitive?
No. RFC 9562 says to treat the hex digits case-insensitively on input and to output them in lowercase. Uppercase is purely cosmetic, but compare UUIDs case-insensitively if your data mixes both.
How do I generate a UUID in code?
JavaScript: crypto.randomUUID(). Python: uuid.uuid4(). Java: UUID.randomUUID(). C#: Guid.NewGuid(). PostgreSQL 13 or later: gen_random_uuid().