How do I generate a UUID?
Choose a type, pick how many you want (up to 5,000) and the values appear straight away. Use the settings to switch to uppercase, remove the hyphens, wrap each one in braces, or output a JSON array instead of one per line. Copy them or download the list as a file.
Which UUID version should I use?
Version 4 is purely random and is the usual default when you just need a unique ID. Version 7 starts with a timestamp, so new values sort after older ones, which keeps database indexes tidy and makes it a good choice for primary keys. Version 5 is different: it's worked out from a namespace and a name, so the same inputs always give the same UUID.
What is a ULID?
A ULID is a 26-character identifier that, like UUID v7, begins with a timestamp so it sorts in creation order. It's written in a case-insensitive alphabet that leaves out easily confused letters, which makes it shorter and friendlier to read than a UUID. ULIDs generated in the same millisecond here are kept in increasing order.
How does the decoder work?
Paste a UUID (with or without hyphens or braces) or a ULID and the tool shows its version and variant. For time-based types (UUID v1, v6, v7 and ULID) it also shows the date and time baked into the value, in UTC.
Are the values really random?
Yes. Random parts come from your browser's cryptographically secure random number generator, the same one used for the password generator, and everything is created on your device. Nothing is sent to a server.
Can two UUIDs ever be the same?
In theory, but with 122 random bits in a version 4 UUID the chance of a clash is so small that it's ignored in practice, even across billions of values.