Inspect a UUID
How to use the UUID generator
- Choose v4 for a random identifier, or v7 for one that sorts by the time it was made.
- Choose how many you need (up to 1,000) and how they should look, then select Generate.
- Copy them, or download them as a text file with one UUID per line. To check an existing UUID, paste it under Inspect a UUID.
Version 4 or version 7?
A version 4 UUID is 122 random bits plus 6 fixed bits that mark its version and variant. Use it whenever you need an ID that reveals nothing.
A version 7 UUID (RFC 9562, 2024) starts with the current time in milliseconds, followed by random bits. New IDs sort after older ones, so database indexes stay compact when it is a primary key. The flip side: anyone holding one can read when it was created, which is exactly what Inspect a UUID shows. Within a single millisecond, a batch from this tool still comes out in order.
Secure randomness, and what “unique” means
Random bits come from your browser’s cryptographically secure generator: crypto.randomUUID() where available, otherwise crypto.getRandomValues(). If your browser has neither, the tool says so and generates nothing; it never falls back to a predictable generator such as Math.random().
The format does not guarantee uniqueness; the randomness makes a repeat extraordinarily unlikely. With 122 random bits, you would need to generate about a billion v4 UUIDs every second for 85 years before a single duplicate became likely. UUIDs are identifiers, not secrets: do not use one as a password or a session token where guessing it would grant access.
UUIDs are made in your browser and are not sent to or stored by this site.