A UUID (Universally Unique Identifier, also called a GUID) is a 128-bit label written as 36 characters — 8-4-4-4-12 hexadecimal digits with hyphens, like 550e8400-e29b-41d4-a716-446655440000. Systems use them to identify records, users, files and sessions without a central counter.

What does version 4 mean?

Version 4 UUIDs are built from random bits — 122 of the 128 bits are random, the rest are fixed markers that say 'this is version 4, variant 1'. This generator uses your browser's cryptographic random source, the same one security software uses.

Could two generated UUIDs ever collide?

In practice, no. With 122 random bits there are about 5.3 × 10³⁶ possible values; you would need to generate billions per second for centuries before a collision became likely. That is why databases and APIs trust them as primary keys.

Are the UUIDs I generate stored anywhere?

No. They are created on your device in this tab and are never sent to or kept on a server. Copy or download them before you close the page.

UUID Generator

Fresh version-4 UUIDs, generated with cryptographic randomness on your device — one at a time, or a bulk list of up to 100.

How many UUIDs (1–100)

Your UUIDs —

How to use it

Choose how many. One for a quick ID, or up to 100 for seeding a database or a test fixture.

Generate. Every UUID is a fresh version-4 value built from your browser's cryptographic random generator.

Copy or download. Take the whole list in one tap — nothing is uploaded or stored.

Where UUIDs earn their keep

Any time two systems must agree on an identity without phoning home, a UUID is the answer: database primary keys that can be created offline and merged later, idempotency keys that stop an API retry from charging a card twice, file names that never overwrite a stranger's upload, and session or correlation IDs in logs. Because a v4 UUID carries no timestamp, no machine address and no sequence, it also leaks nothing about when or where it was made — which is exactly why this page can generate them honestly in your browser with no server involved.

UUID Generator

How to use it

Where UUIDs earn their keep

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