To generate a UUID, choose how many you need under How many and select Generate UUIDs. The tool creates random version 4 UUIDs with your browser's cryptographic random number generator and lists them with individual Copy buttons. Select Copy All, or download the list as TXT, JSON or CSV.
How to use the UUID generator
- Pick a quantity. Under How Many, choose 1, 5, 10, 20, 50, 100, 250, 500 or 1,000 UUIDs.
- Set the format. Choose lowercase or UPPERCASE, a Wrapper Style such as {uuid} or "uuid", an Output Separator, and an Optional Prefix. Tick Remove hyphens for 32-character IDs.
- Generate. Select Generate UUIDs or press Ctrl+Enter. With Check duplicates ticked, the summary confirms that every UUID in the batch is unique.
- Copy or export. Use Copy first UUID, Copy All, or a single UUID's Copy button, or save the batch with Download TXT, Download JSON or Download CSV.
What is a UUID v4 generator?
A UUID (universally unique identifier) is a 128-bit value written as 32 hex digits in five groups, 36 characters with hyphens. The current standard is RFC 9562, published in May 2024, which replaced RFC 4122. A version 4 UUID is random: 122 of its bits come from a random number generator and the other 6 mark the version and variant.
3f6c2a9e-8b1d-4e57-a0c4-9d2f7b6e1a35
^ ^
version 4 variant (8, 9, a or b)The 13th hex digit is always 4, and the 17th is always 8, 9, a or b. This page sets those bits on 16 bytes from crypto.getRandomValues(), the same cryptographic source the browser uses for security keys. Version 4 is the default; switch Version to v7 for time-ordered IDs.
How unique is a random UUID?
Unique enough that you can create IDs on different servers, phones or browsers without checking a central database. With 122 random bits, you would need to generate about 103 trillion version 4 UUIDs to reach a one-in-a-billion chance of a single duplicate, and about 2.71 quintillion for even odds.
That only holds when the randomness is good. UUIDs built with Math.random() in old JavaScript snippets are far easier to predict and collide. The duplicate check here compares every UUID in the current batch, which is a sanity check rather than a guarantee across batches. UUIDs also aren't secrets: don't use them as passwords or reset tokens just because they look random. For those, use the password generator.
UUID vs GUID: output formats for any system
GUID (globally unique identifier) is the name Microsoft uses, and modern GUIDs follow the same standard as UUIDs. The difference is mostly presentation, which the format options cover:
| Setting | Example output | Typical use |
|---|---|---|
| Default | 3f6c2a9e-8b1d-4e57-a0c4-9d2f7b6e1a35 | Databases, APIs, JSON |
| UPPERCASE + {uuid} | {3F6C2A9E-8B1D-4E57-A0C4-9D2F7B6E1A35} | Windows registry, .NET and Visual Studio project files |
| Remove hyphens | 3f6c2a9e8b1d4e57a0c49d2f7b6e1a35 | Compact keys, file names |
| 'uuid' + Comma + new line | '3f6c...1a35', | Pasting into a SQL IN (...) list |
| JSON array | ["3f6c...", "8a1e..."] | Test fixtures and seed data |
The prefix is added before the UUID and inside any wrapper, so user_ with quotes gives "user_3f6c...". Download JSON saves the list with the count and creation time, and Download CSV writes an index,uuid table.
UUID v7 and other versions
Set Version to v7 to generate time-ordered UUIDs. Version 7, added in RFC 9562, starts with a 48-bit Unix timestamp in milliseconds followed by random bits, so new IDs sort by creation time. That keeps database indexes compact when UUIDs are primary keys, and the RFC recommends v7 over the older time-based v1 and v6. Within one batch, IDs made in the same millisecond use a counter so they still come out in sorted order. If you need the same ID every time for the same input, that's a job for a name-based UUID (version 5, built on SHA-1) or a plain content hash from the hash generator.
Version 4 remains the right default when you don't want IDs to reveal when they were made. In your own code, modern browsers and Node.js offer crypto.randomUUID(), which returns a v4 UUID in one call.
The UUID Validator / Inspector on the left of the workspace accepts IDs with or without hyphens, braces or quotes, and reports the version digit, the variant and a normalised lowercase form. It accepts versions 1 to 8 and shows the embedded time for v1, v6 and v7. The special nil UUID (all zeros) and max UUID (all f), both defined in RFC 9562, are reported as valid special values.
Frequently asked questions
Is this a random UUID generator?
Yes. Every UUID is version 4, built from 122 random bits supplied by your browser's cryptographic random number generator. Nothing is generated on or sent to a server.
Can I generate UUIDs in bulk?
Yes. Choose up to 1,000 UUIDs under How Many, then copy them all or download them as a TXT, JSON or CSV file.
Is a GUID the same as a UUID?
Yes, for practical purposes. GUID is Microsoft's name for the same 128-bit identifier. To use this page as a GUID generator, choose UPPERCASE and the {uuid} wrapper, the format Windows tools usually show.
Does this tool generate UUID v7?
Yes. Set Version to v7 (time-ordered). Each v7 UUID starts with the current Unix time in milliseconds, so a list of them sorts by creation time, and the validator can read that time back out.
Can two UUIDs ever be the same?
In theory yes, in practice no. You'd need about 103 trillion version 4 UUIDs for a one-in-a-billion chance of one duplicate, provided they come from a good random source.
Are UUIDs case-sensitive?
No. RFC 9562 treats hex digits as case-insensitive and recommends lowercase output, but some systems store them as plain strings, so stay consistent within one database.