UUID Generator

What exactly is a UUID?

UUIDs follow the RFC 4122 specification and are written as five hexadecimal groups separated by dashes, for example 5f7e7441-1eb7-4b2a-b4a4-5646766587d0.

This tool supports multiple UUID versions: v1 (time-based), v4 (random), v5 (name-based with SHA-1), and v7 (Unix epoch time-based from RFC 9562).

UUID Versions Explained

Version 1 uses the current timestamp and MAC address, making it suitable when you need time-sortable identifiers but with some privacy concerns.

Version 4 is fully random with 122 bits of entropy, making collisions practically impossible. It's the most commonly used version.

Version 5 generates deterministic UUIDs from a namespace and name using SHA-1, useful when you need reproducible identifiers.

Version 7 is a newer standard (RFC 9562) that combines Unix timestamp with random bits, offering both time-sortability and randomness.

Why developers rely on UUIDs

Because UUIDs can be generated without a central authority, they simplify API design, background jobs, and client-side code—you can create the identifier before saving data.

They are also opaque: a UUID reveals nothing about the data it labels, so it is harder to infer volume or sequence information.

Which version to choose?

• Use v4 for most cases - it's simple, random, and widely supported
• Use v1 or v7 when you need time-sortable identifiers in distributed systems
• Use v5 when you need deterministic IDs from known inputs (like URLs or domain names)
• Use v7 for new projects needing time-ordered IDs with better randomness than v1

Good practices after generating

• Normalize the value to lowercase before storing to avoid accidental duplicates
• Store UUIDs in binary form when your database offers native 16-byte columns for better performance
• Avoid exposing predictable sequences—mix UUIDs with additional metadata if you must share them publicly
• Log the context along with the UUID so you can later audit where it was used