UUID Generator

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier) on Windows, is a 128-bit value typically written as 32 hexadecimal digits in five groups separated by hyphens, like 550e8400-e29b-41d4-a716-446655440000. It's designed so that generating one independently, anywhere, produces an identifier that's astronomically unlikely to collide with any other UUID ever generated.

UUID version 4 is generated almost entirely from random or pseudo-random numbers — 122 of its 128 bits are random, with the remaining 6 bits fixed to identify the version and variant per the RFC 4122 spec. It's the most commonly used UUID version today because it needs no coordination, network address, or timestamp — just a good random number source, which this tool provides via crypto.randomUUID().

For v4 UUIDs, you'd need to generate roughly 1 billion UUIDs per second for about 85 years before there's a 50% chance of a single collision — the random space is 2^122, an astronomically large number. In practice, UUID collisions are treated as effectively impossible for any real-world application.

It's a common and reasonable choice, especially for distributed systems where IDs need to be generated independently across multiple servers without coordination. The trade-off: UUIDs are larger than auto-incrementing integers (16 bytes vs 4-8) and, because v4 UUIDs are random rather than sequential, they can hurt index locality and insert performance on some databases at very large scale. Sequential variants like UUIDv7 address this if it matters for your use case.

They're the same concept — GUID is Microsoft's term (used throughout Windows, .NET, and SQL Server) for what the rest of the industry calls a UUID, defined by the same RFC 4122 standard. The formats are interchangeable; code that expects a GUID will accept a UUID generated here without any conversion.