UUID generator

Unique identifiers instantly

No database: AIMRAN doesn't store your files, text or results

What is UUID generator?

A UUID (also called a GUID) is a 36-character unique identifier used in databases, APIs and applications to give every record a name that never repeats. This tool generates them instantly.

You can choose between version 4, fully random, and version 7, which starts with the date and time and therefore sorts chronologically on its own.

How to use it

  1. Choose the version: v4 or v7.
  2. Enter how many UUIDs you need, from 1 to 1000.
  3. Turn hyphens and uppercase on or off.
  4. Click “Copy all” or download them as a text file.

Advantages

Technical details

v4 UUIDs use crypto.randomUUID or, if unavailable, 16 bytes from crypto.getRandomValues with the version (0100) and variant (10) bits set, leaving 122 random bits. v7 UUIDs follow RFC 9562: 48 bits with the Unix timestamp in milliseconds, 4 version bits, 12 bits used as a monotonic counter to keep order within the same millisecond, 2 variant bits and 62 random bits. Because they sort by time, v7 UUIDs reduce B-tree index fragmentation compared with v4 when used as a primary key. The standard format is 8-4-4-4-12 in hexadecimal, optionally without hyphens (32 characters) or in uppercase.

Frequently asked questions

What is a UUID?

A 128-bit universally unique identifier written as 32 hexadecimal characters in 8-4-4-4-12 groups, for example 550e8400-e29b-41d4-a716-446655440000.

What's the difference between UUID v4 and v7?

v4 is fully random. v7 starts with a millisecond timestamp, so identifiers end up sorted by creation date.

Can a v4 UUID repeat?

In practice, no: with 122 random bits you'd have to generate quadrillions to have a noticeable chance of a collision.

Is a UUID the same as a GUID?

Yes. GUID is Microsoft's name for the same 128-bit identifier standard.

Which UUID should I use as a database primary key?

v7 is usually better: because it's time-ordered, new records are inserted at the end of the index and performance is higher than with v4.

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