UUID / GUID Generator
Generate v4 UUIDs, NanoIDs, short IDs or custom-prefixed unique identifiers -- up to 50 at once.
Disclaimer: This tool runs entirely in your browser -- nothing you enter is sent to or stored on our servers.
What a UUID Is, and Why Version 4 Is Standard
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized as a 32-character hexadecimal string in the format 8-4-4-4-12 (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx). UUID version 4 (the most common, and what this generator produces) is randomly generated. The probability of generating two identical UUIDs is astronomically small -- approximately 1 in 5.3 x 1036, making collisions a non-issue in virtually any real-world system.
Common use cases: primary keys in databases (avoids sequential-ID guessing attacks and lets distributed systems generate IDs independently without central coordination); session tokens; file names for user-uploaded content to prevent overwriting; API correlation IDs for request tracing in microservices; and unique event identifiers in analytics systems. For security-critical tokens like password reset links, use a cryptographically secure random generator and consider shorter, URL-safe token formats rather than full UUIDs.
Worked Example
Generating 5 UUID v4 identifiers produces output like 3f2a9c1e-7b4d-4a6f-9e2c-8d1b5f0a3c7e -- each one independently random, each starting its third group with "4" (marking it as version 4) and its fourth group with 8/9/a/b (the RFC 4122 variant bits), which is how a UUID's version can be identified just by inspection.