A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems. It is designed to be unique without central coordination.

What is the difference between UUID v4 and v7?

UUID v4 is fully random. UUID v7 starts with a Unix timestamp, so IDs are sortable by creation time — useful for database primary keys and log entries.

Are these UUIDs cryptographically secure?

Yes. Generation uses the browser's crypto.randomUUID and crypto.getRandomValues, both of which use a cryptographically secure random source.

How many UUIDs can I generate at once?

Up to 100 per click. If you need more, click Generate again to get a fresh batch, or increase the count up to the limit.

Can two UUIDs collide?

In practice, no. UUID v4 has 122 random bits, giving 5.3×10^36 possible values. You would need to generate about 2.7×10^18 UUIDs to have a 50% chance of one collision — trillions per second for centuries.

Which UUID version should I use for a database primary key?

UUID v7 is better for database keys because its time-ordered prefix improves B-tree index locality — new rows append rather than inserting randomly. UUID v4 is fine for non-ordered IDs (session tokens, correlation IDs) but causes index fragmentation in high-insert databases.

UUID Generator

Generate cryptographically secure UUIDs — up to 100 per click. Choose version 4 (fully random) or version 7 (time-ordered, sortable by creation time). Toggle uppercase or lowercase, with or without dashes. Copy results with one click.

How to use

Choose the version

Select v4 (random) or v7 (time-ordered).

Set the count

Enter how many UUIDs you need — up to 100 per batch.

Set formatting options

Choose uppercase or lowercase, and whether to include dashes.

Generate and copy

Click Generate and copy the results to your clipboard.

v4 (random)v7 (time-ordered)

Count

UppercaseNo dashes

Click Generate to create UUIDs.

Features

UUID v4 and v7

v4 is fully random; v7 starts with a timestamp and is sortable by creation time.

Bulk generation

Create up to 100 UUIDs per click.

Custom formatting

Uppercase or lowercase, with or without dashes.

Cryptographically secure

Uses crypto.randomUUID and crypto.getRandomValues.

Common use cases

Generate primary keys for a database
Create unique identifiers for API resources
Produce IDs for log entries
Generate a batch of UUIDs for testing

Frequently Asked Questions

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