A 128-bit identifier whose value is almost entirely random (122 random bits). The chance of two v4 UUIDs colliding is negligible — roughly one in 2¹²².

Where is the randomness from?

The browser's crypto.randomUUID, backed by the operating system's secure random source — not Math.random.

What is the difference between UUID v1, v4 and v7?

Version 1 combines time with a node identifier, version 4 is almost entirely random, and version 7 is time-ordered for better database index locality. This tool generates version 4, which is the most common choice for general-purpose identifiers.

Can I use these UUIDs as database primary keys?

Yes. Random v4 keys are safe and distributed; their downside is that insert order is random, which can fragment B-tree indexes. If index locality matters, use a time-ordered format such as UUID v7 or ULID.

Are UUIDs guaranteed to be unique?

Not mathematically, but a v4 UUID has 122 random bits, so the chance of a collision is far smaller than hardware failure rates. Treat them as unique in practice — but never as secrets, since identifiers may be logged or exposed in URLs.

UUID Generator

Generate v4 UUIDs — one or a batch, any casing.

Frequently asked questions

What is a UUID v4?: A 128-bit identifier whose value is almost entirely random (122 random bits). The chance of two v4 UUIDs colliding is negligible — roughly one in 2¹²².
Where is the randomness from?: The browser's crypto.randomUUID, backed by the operating system's secure random source — not Math.random.
What is the difference between UUID v1, v4 and v7?: Version 1 combines time with a node identifier, version 4 is almost entirely random, and version 7 is time-ordered for better database index locality. This tool generates version 4, which is the most common choice for general-purpose identifiers.
Can I use these UUIDs as database primary keys?: Yes. Random v4 keys are safe and distributed; their downside is that insert order is random, which can fragment B-tree indexes. If index locality matters, use a time-ordered format such as UUID v7 or ULID.
Are UUIDs guaranteed to be unique?: Not mathematically, but a v4 UUID has 122 random bits, so the chance of a collision is far smaller than hardware failure rates. Treat them as unique in practice — but never as secrets, since identifiers may be logged or exposed in URLs.

About this tool

A UUID is a 128-bit identifier designed to be unique without coordination between systems. Version 4 UUIDs are generated from secure random bytes, which makes collisions vanishingly unlikely. This generator creates one or a batch, with optional uppercase and hyphen-free formatting for systems that expect either style.

How to use it

Set how many UUIDs you need (up to 50).
Toggle uppercase letters or remove hyphens to match the target system.
Copy the first UUID from the main result or copy the whole batch from the code panel.
Paste them into your database, fixtures or test data.

← All tools