Generate random version 4 UUIDs.
A UUID generator is an essential tool for developers who need unique identifiers for database records, session tokens, API keys, or any system requiring globally unique values. This free online UUID generator produces cryptographically random version 4 UUIDs instantly in your browser using the native crypto API — no data ever leaves your machine. Generate up to 100 UUIDs at once in lowercase or uppercase format, then copy them all with a single click.
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) refer to the same 128-bit identifier format. GUID is Microsoft's terminology used in Windows and .NET environments, while UUID is the standard term defined by RFC 4122. They are fully interchangeable and follow the same structure.
A version 4 UUID is generated using cryptographically random bits — 122 bits of randomness in total. The remaining bits encode the version (4) and variant. The probability of generating two identical v4 UUIDs is astronomically small (roughly 1 in 5.3 × 10^36), making collisions practically impossible for any real-world workload.
Yes. Version 4 UUIDs are widely used as primary keys in distributed systems because they can be generated on any client without a central coordinator and are guaranteed to be unique. The main trade-off compared to sequential integer IDs is slightly larger storage and less optimal B-tree index performance in some databases, but this is acceptable in most applications.
Once the page has loaded, yes. This tool runs entirely in your browser using the built-in crypto.randomUUID() API — no network request is made to generate UUIDs. Your identifiers are never sent to any server, making this tool safe for generating IDs even in sensitive or air-gapped environments.