How to Generate UUID v4: The Free Online Guide for Developers
Learn what UUIDs are, when to use them, and how to generate UUID v4 identifiers for free online. Bulk generation supported — no account needed.
UUIDs are the go-to solution for unique identifiers in distributed systems, database primary keys, and API resource IDs. This guide explains what UUIDs are, when to use them, and how to generate them for free.
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier represented as 32 hex digits separated by hyphens: e.g. 550e8400-e29b-41d4-a716-446655440000. UUID v4 uses cryptographically random bytes — the collision probability is approximately 1 in 5 quintillion.
When do you need UUIDs?
- •Database primary keys — avoid predictable sequential IDs
- •Distributed systems — generate unique IDs across servers without coordination
- •API resource identifiers — /users/{uuid} endpoints
- •Uploaded file names — prevent filename collisions on storage
- •One-time tokens — email verification links, password reset tokens
How to generate UUIDs with ProUtils
- 1Go to the UUID Generator tool.
- 2Set the number of UUIDs to generate.
- 3Click "Generate".
- 4Copy the UUIDs.
UUID versions compared
UUID v1 (timestamp-based)
UUID v1 is based on the current timestamp and MAC address. Time-ordered but exposes the MAC address, which is a privacy concern.
UUID v4 (random)
UUID v4 is generated from cryptographically random bytes. Unpredictable, no personal information exposed. The most widely used version today.
UUID v7 (sortable random)
UUID v7 combines a millisecond-precision timestamp with random data. Time-sortable like v1 but without MAC exposure. A good choice for new systems where database index performance matters.
Frequently asked questions
Are UUID v4 values truly unique?
The collision probability for UUID v4 is roughly 1 in 5 quintillion. For all practical purposes, they are unique.
Is the UUID generator free?
Yes. The ProUtils UUID Generator is completely free with no account required. Bulk generation of multiple UUIDs at once is supported.
Are generated UUIDs stored anywhere?
No. UUIDs are generated entirely in your browser using the Web Crypto API. Nothing is sent to a server.
Need UUIDs now? Try the ProUtils UUID Generator — free, instant, bulk-generation supported.