About the Handiwork UUID Generator
The UUID Generator creates universally unique identifiers (UUIDs/GUIDs) on demand. Generate random version 4 UUIDs or time-based version 1 UUIDs, produce them one at a time or in bulk, and copy them straight into your database, code, or configuration.
How to use the Handiwork UUID Generator
- Choose the UUID version (v4 random or v1 time-based).
- Generate a single UUID or a batch of them.
- Copy the identifiers you need.
UUID v4 vs. v1
UUID v4 is generated from random bits and is the common default because it reveals no creation time. UUID v1 includes a 100-nanosecond timestamp measured from the UUID epoch. This generator uses a random node identifier with its multicast bit set, so it does not expose a device MAC address. The standard text form is not reliably chronological when sorted as a string; use UUIDv7 when database sort order is the goal.
Why use UUIDs?
UUIDs let independent systems create unique identifiers without coordinating with a central authority, which avoids collisions when merging data, generating database primary keys, naming files, or tracking distributed events.
How each version is actually generated
Version 4 UUIDs call the browser’s native crypto.randomUUID(), the same cryptographically secure method browsers expose for this exact purpose. Version 1 UUIDs are assembled by hand following RFC 9562’s layout: a 60-bit timestamp in 100-nanosecond intervals since the UUID epoch (15 October 1582), a random clock sequence, and a random 48-bit node value with its multicast bit set so it can never be mistaken for a real network hardware address.
Reading the UUID format
A UUID is 32 hex digits shown as five hyphen-separated groups (8-4-4-4-12). One nibble encodes the version (4 for random, 1 for time-based), and two bits near the start of the fourth group encode the variant, which for both versions here is the standard RFC 9562 variant (the digit appears as 8, 9, a, or b).
Continue this workflow
Use the adjacent tool when the next step calls for a different input, output, or method.
Assumptions and limitations
- UUID uniqueness is probabilistic, not mathematically guaranteed. Systems with strict collision requirements should still enforce a unique constraint.
- UUIDv1 embeds a timestamp and should not be used when creation-time disclosure is undesirable. This implementation uses a random node identifier rather than a hardware address.
- The canonical UUIDv1 string layout is not chronological under ordinary text sorting. Prefer a UUID version designed for sortable identifiers when ordering is a requirement.
Sources and standards
These authoritative references were used to verify the method and guidance on this page.
Frequently asked questions
Are these UUIDs really unique?
UUID v4 has 122 bits of randomness, making collisions astronomically unlikely — for practical purposes you can treat each generated value as unique.
What is the difference between a UUID and a GUID?
They are the same thing. GUID (Globally Unique Identifier) is Microsoft’s name for a UUID; the format is identical.
Does UUID v1 reveal my MAC address?
Not in this generator. It uses a random 48-bit node identifier and sets the multicast bit, as the UUID standard permits for nodes that are not hardware addresses.
How is the version encoded in the UUID string?
Look at the first character of the third group of digits: a 4 there means version 4 (random), and a 1 means version 1 (time-based) — for example 4a1b... vs 1a1b... in that position.