Generators
UUID Generator
Generate random version-4 UUIDs (GUIDs) for databases, APIs and software development.
About the UUID Generator
The UUID Generator creates random version-4 universally unique identifiers, up to 500 at a time. Format them in uppercase, without hyphens, in braces or as quoted, comma-separated values ready for code, then copy or download the list. A built-in checker tells you whether any UUID is valid and which version it is.
What you can do with the UUID Generator
- Up to 500 at once: Random version-4 UUIDs.
- Code-ready formats: Uppercase, no hyphens, braces or quoted lists.
- Copy or download: Take the whole list.
- UUID checker: Validate any UUID and see its version.
Why UUIDs are "unique"
A version-4 UUID has 122 random bits, giving about 5.3 × 10³⁶ possible values. You would need to generate around 2.7 quintillion UUIDs to have even a 50% chance of a single duplicate, which is why systems can create IDs independently without checking with each other.
Reading the format
The first digit of the third group is the version, 4 for random UUIDs, 7 for the newer time-ordered kind. The first digit of the fourth group is 8, 9, a or b for the standard variant. Paste a UUID into the checker to read these for you.
UUID or GUID? And what about v7?
GUID is Microsoft's name for the same thing, often written in uppercase inside braces. Version 7 starts with a timestamp so IDs sort by creation time, which can make database indexes more efficient. Version 4, generated here, is fully random and the most widely supported.
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Frequently Asked Questions
Can two UUIDs ever be the same?
In theory yes, but the probability is so small that it's treated as impossible in practice.
How do I get GUIDs in Microsoft format?
Switch on UPPERCASE and { Braces }.
Are these UUIDs safe to use as secret tokens?
They're generated with secure randomness, but UUIDs are designed as identifiers, not secrets. Use the Password Generator for passwords or API keys.
What is the difference between a UUID and a GUID?
They are the same kind of 128-bit identifier. GUID is the name Microsoft uses, often written in uppercase inside braces, while UUID is the standard name. Switch on UPPERCASE and { Braces } here to get the GUID style used in Windows and .NET.
How can I tell a UUID is version 4?
Look at the first digit of the third group: in a version-4 UUID it is always 4, as in xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The first digit of the fourth group is 8, 9, a or b for the standard variant. The Check a UUID box reads both for you.
What is the difference between UUID v4 and v7?
Version 4 is fully random, while version 7 starts with a timestamp, so v7 values sort roughly by creation time, which can suit database indexes. This tool generates version 4 only, but the checker recognises v7 and other versions when you paste them.
How long is a UUID?
A UUID is 128 bits, written as 32 hexadecimal digits. With the usual hyphens in the 8-4-4-4-12 pattern it is 36 characters long, or 32 if you switch on No hyphens. Stored as binary in a database, it takes 16 bytes.
How do I paste a list of UUIDs into SQL or code?
Switch on "Quotes" to wrap each UUID in double quotes with a comma after it; the last comma is removed. The list is ready to drop into a JSON array or a code list. For SQL, which usually expects single quotes, swap the quote marks after copying.
Are uppercase and lowercase UUIDs the same?
Yes. The hex letters a to f mean the same in either case, and the standard says UUIDs should be compared without regard to case. Lowercase is the usual output, but some systems such as Windows tools show them in uppercase.
How many UUIDs can I generate at once?
Up to 500 at a time, set with the How many UUIDs stepper. Copy the whole list or download it as a file, which helps when seeding a test database or creating IDs for a batch of records.
Will the checker accept a UUID with braces or no hyphens?
Yes. It strips surrounding braces, quotes and a trailing comma, and accepts the 32 hex digits with or without hyphens. If it says the UUID is not valid, check for missing or extra characters, or letters beyond f, which are not hexadecimal.
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