UUID Generator

What a UUID is

A UUID (universally unique identifier) is a 128-bit label written as 32 hexadecimal digits in five groups, like 705e41a3-d432-4aa9-9ea4-4693bf481eaa. The format is defined in RFC 9562. Programs use UUIDs as IDs for database rows, files, API requests and messages, because anyone can create one without asking a central server, and the chance of two being the same is too small to matter.

Two digits in every UUID carry meaning. The first digit of the third group is the version, so a version 4 UUID always has a 4 there and a version 7 UUID has a 7. The first digit of the fourth group is the variant, which is always 8, 9, a or b for standard UUIDs.

How to use the UUID generator

1. Under Version, choose Version 4 (random) or Version 7 (time ordered).
2. Set How many. You can make up to 1,000 in one go. The default is 5.
3. Pick your format under Options:
   • Uppercase for capital A to F.
   • Hyphens is on by default. Turn it off for a 32 character string.
   • {Braces} wraps each UUID in curly brackets, the style used in Windows and the registry.
4. Choose how to Separate results with. New line is the default.
5. Press Generate UUIDs, then Copy.

Your last ten batches stay under Recent results until you leave the page. Press Clear to remove them sooner.

Examples

All of these were made by the code behind this page.

Notice how the version 7 IDs share their first 12 digits. Those digits are the time stamp, 01a1063fb1c0 in hex, which is 1791106200000 milliseconds since 1 January 1970. That is exactly 4 October 2026 at 09:30 UTC.

How it works

Version 4. The tool calls crypto.randomUUID(), the browser’s built-in UUID function. It fills 122 bits from a cryptographically secure random source and sets the version and variant bits.

Version 7. The first 48 bits are the current Unix time in milliseconds. Next come the version digit and 12 more bits, then the variant and 62 random bits. When you make many IDs in the same millisecond, the 12 bits after the version act as a counter that goes up by one each time. That keeps a batch in strict order: if you sort the list as text, you get the order it was made in. The random bits come from crypto.getRandomValues.

Which version should you use?

• Version 4 is the safe default when you just need a unique ID. It reveals nothing about when or where it was made.
• Version 7 is a good choice for database primary keys. New rows land at the end of the index instead of at random places, which tends to keep indexes compact and inserts fast. The trade-off is that anyone who sees the ID can read its creation time.

Tips and limits

• Store UUIDs in a native column where your database has one, such as uuid in PostgreSQL. It takes 16 bytes instead of 36 characters of text.
• Lowercase is the standard form. UUIDs are not case sensitive, but RFC 9562 says to output lowercase. Use Uppercase only when a system asks for it.
• Not a secret. Do not use UUIDs as passwords or reset links. Use the strong password generator for anything that must be hard to guess.
• Need a fingerprint, not an ID? A hash such as MD5 or SHA-256 identifies content. Try the MD5 hash generator.
• Test data. For fake network addresses to go with your IDs, use the random IP address generator.

Other ways to make a UUID

Command line. On macOS and most Linux systems, uuidgen prints a new UUID. In PowerShell, use New-Guid or [guid]::NewGuid().

JavaScript. crypto.randomUUID() works in modern browsers and in Node.js.

Python. import uuid then uuid.uuid4(). Python 3.14 also adds uuid.uuid7().

Databases. PostgreSQL has gen_random_uuid() for version 4, and version 18 adds uuidv7(). SQL Server has NEWID().

Excel. There is no built-in UUID function. Generate a list here, copy it, and paste it into a column.