UUID Generator
Generate a random version-4 UUID and copy it instantly.
How to use
- A UUID is generated automatically.
- Click Generate new for another.
- Click Copy to grab it.
How the UUID Generator works
Generates version 4 UUIDs — 128-bit random identifiers used as database keys, request IDs and anywhere you need uniqueness without a central authority.
It uses crypto.randomUUID() where available, which is the browser's native cryptographically secure implementation, falling back to a getRandomValues-based construction otherwise. Version 4 UUIDs are random apart from fixed version and variant bits.
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (4 = version, y ∈ {8,9,a,b} = variant)
Worked example
A generated value looks like 3f2504e0-4f89-41d3-9a0c-0305e82c3301 — the 4 in the third group marks it as version 4.
Things worth knowing
- Version 4 UUIDs have 122 random bits. You would need to generate about 2.7×10¹⁸ of them before a collision becomes likely.
- They are random, so they do not sort meaningfully and can fragment database indexes. UUIDv7, which embeds a timestamp, is the better choice for primary keys in new systems.
- A UUID is an identifier, not a secret. Do not use one as an authentication token.
Frequently asked questions
What is a UUID?
A universally unique identifier — a 128-bit value used to label data with near-zero chance of collision.
Is this a valid v4 UUID?
Yes — it follows the version-4 random format and uses a cryptographic source when available.
What is the difference between UUID v4 and v1?
v1 encodes a timestamp and the machine's MAC address, which makes it sortable but leaks information. v4 is purely random and leaks nothing.
Are UUIDs guaranteed unique?
Not guaranteed, but the collision probability is so small it is safely ignored in practice.