Generate one or a thousand UUIDs — random v4 or sortable v7 — in the format you need, or paste a UUID to check that it's valid and see which version it is.
Paste any UUID or GUID to check it and read its version.
We use UUID v7 keys in Pyalm's own offline-first apps, like Pyalm Books on Android. Need an app that syncs reliably? That's what we build.
A UUID is a 128-bit identifier that can be generated anywhere — in the browser, on a phone offline, on any server — with practically no chance of collision. That makes UUIDs ideal for database keys in distributed and offline-first apps, file names and request IDs.
UUID v4 is fully random. UUID v7 starts with a millisecond timestamp, so new IDs sort after older ones. That keeps database indexes compact and inserts fast, which is why v7 is now the recommended choice for primary keys.
📖 Read the full guide: UUID v4 vs v7: Which Should You Use for Database IDs?
Yes. They are generated with the browser's cryptographically secure random number generator (crypto.getRandomValues), the same source used for encryption keys.
In theory, yes; in practice, no. A v4 UUID has 122 random bits — you would need to generate billions per second for decades before a collision became likely.
None in practice. GUID is Microsoft's name for the same 128-bit identifier format.
They work well, especially when IDs must be created on clients or across several databases. Prefer v7 over v4 for primary keys so new rows are inserted in index order.