Generate random v4 or time-ordered v7 UUIDs, up to 1,000 at once, and check what version an existing UUID is.
v7 for database keys that sort by time; v4 when you want pure randomness.
Up to 1,000 at once, with or without hyphens, upper case or braces.
Copy all at once, or paste a UUID to see its version.
v7 (RFC 9562) starts with a timestamp, so new IDs sort after old ones and database indexes stay fast. v4 is fully random and reveals nothing about when it was made.
In practice, no. Even generating a billion a second, a v4 duplicate would take about 85 years to become likely.
No. They’re made in your browser with crypto.getRandomValues, so nobody else sees them.