How to Generate a UUID (v4)
UUIDs give you unique identifiers without a central counter, so independent systems can create IDs that never clash. Here's how to generate a v4 UUID and when you'd want one.
Last updated: July 2026
A UUID (universally unique identifier) is a 128-bit value written as 36 characters, like 550e8400-e29b-41d4-a716-446655440000. Version 4 UUIDs are random, so the odds of two ever colliding are astronomically small — ideal as database keys or API identifiers. To generate one, open a UUID generator and copy the value; it's created locally in your browser.
Generate random v4 UUIDs (GUIDs) in bulk and copy them with one click. Free, instant and fully in-browser using the secure crypto API.
Step by step
- Open the free UUID Generator.
- Generate a random v4 UUID.
- Copy it (or generate several at once).
- Use it as a primary key, request ID or unique reference.
What is a v4 UUID?
A version-4 UUID is generated from random numbers (per RFC 9562, which supersedes RFC 4122). It's 128 bits — 122 of them random — so collisions are effectively impossible in practice, which is why they're safe to generate independently across many machines.
When should I use a UUID?
Use one when you need a unique ID without coordinating with a database sequence — distributed systems, offline-first apps, public identifiers you don't want to be guessable or enumerable, and merge-friendly keys.
FAQ
Can two UUIDs collide?
In theory yes, but the probability for v4 is so small it's ignored in practice — you'd need to generate billions per second for many years.
Is it generated privately?
Yes — the UUID is created in your browser and never sent anywhere.
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