UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across space and time. UUIDs are used to identify resources in distributed systems, databases, and APIs without requiring a central authority to issue IDs.

UUID v4 is completely random. UUID v7 is time-based and sortable — it starts with a Unix timestamp, making it ideal for database primary keys since it preserves insertion order while remaining unique.

For UUID v4, the probability of collision is astronomically low — about 1 in 2^122. You'd need to generate about 2.7 quintillion UUIDs to have a 50% chance of one collision.

UUID and GUID (Globally Unique Identifier) are essentially the same thing. GUID is the term used primarily by Microsoft, while UUID is the standard name used in RFC 4122 and RFC 9562.

The canonical format includes hyphens (8-4-4-4-12), but both formats are valid. Hyphens improve readability. Some systems strip hyphens for storage efficiency.

Use UUID v7 when you need time-ordered identifiers, such as database primary keys. Because v7 embeds a Unix timestamp in the most significant bits, UUIDs sort chronologically, which dramatically improves B-tree index performance and insertion speed in databases like PostgreSQL and MySQL. Use v4 when ordering does not matter and pure randomness is preferred.

This tool supports bulk generation of up to 1,000 UUIDs in a single batch. You can copy all generated UUIDs to your clipboard or download them as a text file. For most testing and development scenarios, generating 5-100 UUIDs at a time is typical.

No. Per RFC 4122, UUIDs are case-insensitive. The hexadecimal characters a-f and A-F are treated as equivalent. However, the canonical representation uses lowercase, and most systems normalize UUIDs to lowercase for consistency. This tool lets you toggle between lowercase and uppercase output.