UUID v1 Generator
Create version 1 UUIDs built from a clock reading and a node ID, and decode the timestamp they carry.
Processed locally in your browser/ Your data stays in your browser.
What is UUID v1 Generator?
A version 1 UUID packs a 60-bit timestamp counted in 100-nanosecond ticks since 15 October 1582 (the start of the Gregorian calendar), a 14-bit clock sequence that avoids repeats when the clock goes backwards, and a 48-bit node ID that originally was the MAC address of the machine.
This generator fills the node with random bytes and sets the multicast bit, as RFC 9562 prescribes for non-hardware nodes, so nothing about your device is exposed. You can also fix a start time or a node ID. The first UUID is decoded into its timestamp, clock sequence and node, and a table shows the timestamp of each one.
How does it work?
- Choose how many UUIDs you need (1 to 1,000).
- Optionally enter a start time (ISO date or Unix seconds) or a 12-digit node ID; leave both empty for the current time and a random node.
- Pick the formatting (uppercase, hyphens, wrapper, separator) and the output format, then click Generate.
- Read the decoded timestamp, clock sequence and node under the result, then copy or download the list.
Common use cases
- Reproducing legacy systems that still store v1 identifiers, such as older Cassandra or Windows tooling.
- Making test fixtures whose creation time is known and fixed by using a chosen start time.
- Teaching how a UUID encodes time, clock sequence and node.
- Checking that a parser correctly extracts the timestamp from a v1 value.
Examples
Create version 1 UUIDs built from a clock reading and a node ID, and decode the timestamp they carry.
Privacy
UUID v1 Generator runs entirely in your browser. The text or files you provide are processed on your device and are not uploaded, logged or stored on our servers.
Limitations
A v1 UUID reveals when it was created and, with a real node ID, which machine made it. Prefer v4 for opaque IDs or v7 for sortable database keys.
Frequently asked questions
Why do consecutive v1 UUIDs not sort by time as strings?
The low bits of the timestamp come first in the text, so the string order does not follow the creation order. Version 6 reorders the same fields to be sortable, and version 7 uses Unix milliseconds.
Does this leak my MAC address?
No. The node is random bytes with the multicast bit set, which is the way RFC 9562 marks a node that is not a real network card. You only get a MAC-like node if you type one yourself.
How can 10,000 UUIDs share one millisecond?
The timestamp counts 100 ns ticks, so a millisecond holds 10,000 distinct values. Within a batch each UUID uses the next tick, which keeps them unique and increasing.
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