How to use the UUID Generator
- Copy the UUID shown, or click Generate for a new one.
- Choose v4 (random) or v7 (time-ordered, better for database keys).
- Set how many you need — up to 1,000 — and the output format.
- Copy all or download as a text file.
v4 or v7?
UUID v4 is 122 bits of randomness. It reveals nothing and is the right default for IDs exposed to users, tokens and correlation IDs.
UUID v7 (RFC 9562, 2024) starts with a millisecond timestamp, so IDs created later sort later. As a database primary key it keeps B-tree indexes compact and inserts fast, which random v4 keys do not. The trade-off: anyone can read the creation time from a v7 ID.
| v4 | v7 | |
|---|---|---|
| Sortable by time | No | Yes |
| Reveals creation time | No | Yes |
| Random bits | 122 | 74 |
| Best for | Public IDs, tokens | Database primary keys, logs |
Will a UUID ever collide?
With 122 random bits, you would need to generate about 2.7 quintillion v4 UUIDs to reach a 50% chance of a single duplicate. At a billion per second, that takes 85 years. In practice, collisions only happen when the random source is broken — which is why these are generated with your browser’s cryptographic generator (crypto.getRandomValues), not Math.random().
Frequently asked questions
What is the difference between a UUID and a GUID?
None in practice. GUID is Microsoft’s name for the same 128-bit identifier. Windows tools often show GUIDs in uppercase with braces, which the format options here reproduce.
Are these UUIDs secure enough for session tokens?
v4 UUIDs from a cryptographic source are unguessable, but a dedicated token of 256 random bits is the better choice for secrets. Never use v7 for secrets — part of it is a predictable timestamp.
Are generated UUIDs stored anywhere?
No. They are generated in your browser and never transmitted.