How to Generate a UUID: Online, Python, JavaScript, SQL & Excel

To generate a UUID, open our UUID generator, set how many you need (1 to 1,000) and press Generate. You get random version 4 UUIDs like 3f2b8c1e-9a4d-4e7b-b1c2-5d6e7f8a9b0c, created by your browser's cryptographically secure crypto.randomUUID(). Tick Uppercase if your system wants capitals, then copy.

In code, it is usually one line: uuid.uuid4() in Python, crypto.randomUUID() in JavaScript, UUID.randomUUID() in Java and gen_random_uuid() in PostgreSQL. Details for each, plus Excel, Linux and Postman, are below.

What a UUID is

A UUID (universally unique identifier) is a 128-bit number written as 32 hexadecimal digits in five groups: 8-4-4-4-12. It lets different computers create IDs independently without checking a central counter and still not collide.

In 3f2b8c1e-9a4d-4e7b-b1c2-5d6e7f8a9b0c:

• The first digit of the third group (4) is the version.
• The first digit of the fourth group (b) is the variant; for standard UUIDs it is always 8, 9, a or b.

UUID v4 vs v7

The current standard, RFC 9562 (published 2024), defines several versions. Two matter for most people:

Use v4 when you want an ID that gives nothing away. Use v7 for database keys where insert performance and natural ordering matter. Our generator makes v4 only; for v7, use your language or database as shown below.

Older versions exist too: v1 (time plus MAC address, which leaks the machine's identity), and v3/v5 (derived from a name by hashing, so the same input always gives the same UUID).

How to generate a UUID in Python

import uuid
str(uuid.uuid4())     # '9b1d...' random v4
uuid.uuid4().hex      # same, without dashes
uuid.uuid7()          # time-ordered v7, Python 3.14 and later

uuid.uuid5(uuid.NAMESPACE_URL, 'https://example.com') gives the same UUID every time for the same name.

How to generate a UUID in JavaScript

• Browsers and Node.js: crypto.randomUUID() returns a v4 UUID string. In browsers it requires a secure context (HTTPS or localhost).
• Without dashes: crypto.randomUUID().replaceAll('-', '')
• v7 in JavaScript: there is no built-in function yet; the popular uuid package on npm provides v7() as well as v4().

Avoid hand-rolled generators built on Math.random(). They are not cryptographically secure and are more likely to collide.

How to generate a UUID in Java

UUID.randomUUID().toString() from java.util.UUID gives a v4 UUID. UUID.nameUUIDFromBytes(bytes) gives a name-based v3 UUID.

How to generate a UUID in PostgreSQL

• SELECT gen_random_uuid(); gives a v4 UUID. It is built in from PostgreSQL 13; older versions need the pgcrypto extension.
• SELECT uuidv7(); gives a v7 UUID in PostgreSQL 18 and later.
• As a column default: id uuid PRIMARY KEY DEFAULT gen_random_uuid().

In MySQL, SELECT UUID(); returns a v1 UUID; in SQL Server, NEWID() returns a random GUID.

Generate a UUID in Linux, Mac and Windows

• Linux and Mac: uuidgen (on Linux, uuidgen -r forces a random one).
• Linux: cat /proc/sys/kernel/random/uuid
• Windows PowerShell: New-Guid or [guid]::NewGuid()

How to generate a UUID in Postman

Use the built-in dynamic variables {{$guid}} or {{$randomUUID}} in a request body, header or URL. Postman fills in a fresh value every time the request is sent.

How to generate a UUID in Excel

Excel has no UUID function. This formula builds a string in v4 format:

=LOWER(DEC2HEX(RANDBETWEEN(0,4294967295),8)&"-"&DEC2HEX(RANDBETWEEN(0,65535),4)&"-4"&DEC2HEX(RANDBETWEEN(0,4095),3)&"-"&DEC2HEX(RANDBETWEEN(32768,49151),4)&"-"&DEC2HEX(RANDBETWEEN(0,16777215),6)&DEC2HEX(RANDBETWEEN(0,16777215),6))

Two cautions:

• RANDBETWEEN recalculates every time the sheet changes, so the IDs keep changing. Copy the cells and use Paste Special > Values to freeze them.
• Excel's random numbers are not cryptographically secure. Fine for test data; for real IDs, generate them with our UUID generator (up to 1,000 at once) and paste them into the sheet.

What is a Minecraft UUID?

In Minecraft Java Edition, every player account has a UUID assigned by Mojang, used by servers to track players even after a name change. You cannot generate your UUID; you look it up from your username (many server tools and community sites do this). Offline-mode servers instead derive a name-based UUID from the player's name. A random UUID generator, including ours, gives new random IDs, which are useful for things like data packs or custom entities, but it will not give you a player's UUID.

Are UUIDs secure?

A v4 UUID from crypto.randomUUID() is unpredictable, so it can work as a hard-to-guess identifier, for example in an unlisted share link. But it was designed to be unique, not to be a secret:

• v1 and v7 UUIDs contain timestamps and are partly predictable.
• UUIDs often end up in logs and URLs.

For passwords, use the password generator. For API keys or tokens, use a dedicated random token of at least 128 bits. If you need a fingerprint of data rather than a random ID, use a hash such as SHA-256 with the SHA-256 hash generator; see our guide on checking a file's SHA-256 hash.

Common mistakes

• Using Math.random() or a home-made function instead of a real UUID generator.
• Storing UUIDs as text in a database that has a native uuid type. The native type is smaller and faster.
• Using random v4 UUIDs as the clustered primary key on very large, insert-heavy tables, where v7 would perform better.
• Assuming case matters. UUIDs are case-insensitive; ABC... and abc... are the same ID, though lowercase is the usual convention.
• Forgetting to freeze Excel formulas, so the IDs change on every edit.

Questions