Key takeaways
- A UUID (universally unique identifier) is a 128-bit value, usually shown as 32 hex characters, designed to be unique without a central registry.
- Common uses: database primary keys, API request IDs, session tokens, and placeholder IDs in test data.
- UUID Generator creates version-4 (random) UUIDs instantly, with no account or install needed.
- Collisions are astronomically unlikely — you don't need to check a generated UUID against anything.
When a UUID is the right choice
- Distributed systems — when multiple services generate IDs independently, UUIDs avoid them colliding, unlike auto-incrementing numbers.
- Public-facing IDs — a UUID in a URL doesn't reveal how many records exist (an ID like `/orders/4821` does).
- Test and mock data — quickly generate placeholder IDs for a dataset without wiring up a real database.
Generating one
Open UUID Generator and copy the generated value — press generate again for a new one each time, including generating several at once if you need a batch.
Frequently asked questions
Are these UUIDs guaranteed unique?
Version-4 UUIDs are generated from 122 random bits — the odds of a collision are so small (roughly 1 in 2.7 quintillion for two to collide) that they're treated as unique in practice.
Can I use a UUID as a database primary key?
Yes, commonly done — just note UUIDs take more storage space than a simple integer and don't sort chronologically, which matters for some database performance patterns.