UUID v1 Generator
Generate up to 10,000 time-based UUID v1 values at once from the current timestamp, a clock sequence and a random node ID. Copy them or download a .txt file. Each UUID v1 records when it was created, in 100-nanosecond steps. If you need IDs that also sort by time, use UUID v7 instead.
What is UUID v1?
UUID version 1, defined in RFC 9562 (formerly RFC 4122), is built from the clock: a 60-bit timestamp counting 100-nanosecond intervals since October 15, 1582, a 14-bit clock sequence, and a 48-bit node ID. The node ID was originally the computer's MAC address. Browsers cannot read MAC addresses, so this tool (which uses the uuid JavaScript library) uses a random node ID instead.
v1 is mostly used today for compatibility with systems that expect it, such as Cassandra's timeuuid type.
How to use
- Enter how many UUIDs you need in Number of UUIDs (v1) (1 to 10,000).
- Click Generate.
- The UUIDs appear one per line. Use the buttons in the corner of the list to copy them, download them as
uuid1.txt, or view them full screen.
Features
- Generates 1 to 10,000 UUIDs per click
- Standard lowercase 8-4-4-4-12 format (36 characters)
- Copy all at once or download as a text file with one UUID per line
- Random node ID, so your device's MAC address is never included
- The last list and quantity are kept in this browser for next time
Layout of a UUID v1
When several UUIDs are generated in a row, usually only the first block changes, because it holds the fastest-moving part of the timestamp:
61a50000-bf23-11f1-92a7-f7b371371e39
61a50001-bf23-11f1-92a7-f7b371371e39
61a50002-bf23-11f1-92a7-f7b371371e39
| Block | Example | Contents |
|---|---|---|
| 1 | 61a50000 | Low 32 bits of the timestamp |
| 2 | bf23 | Middle 16 bits of the timestamp |
| 3 | 11f1 | Version digit 1 + high 12 bits of the timestamp |
| 4 | 92a7 | Variant bits + 14-bit clock sequence |
| 5 | f7b371371e39 | 48-bit node ID (random here) |
Because the low bits of the time come first, sorting v1 strings alphabetically does not put them in creation order.
FAQ
Does a UUID v1 from this tool contain my MAC address?
No. The node ID is random because browsers have no access to the network hardware. UUID v1 values made by other software may contain a real MAC address, which is one reason v1 is not recommended for IDs that are shown publicly.
Can I read the creation time from a UUID v1?
Yes. Put the timestamp bits back in order (block 3 without the leading 1, then block 2, then block 1) to get the number of 100-nanosecond intervals since 1582-10-15 UTC.
Should I use UUID v1 or UUID v7?
For new designs, RFC 9562 recommends UUID v7: it is also time-based but sorts in creation order and does not need a node ID. Choose v1 only when an existing system requires it.
Are the generated UUIDs sent anywhere?
No. They are generated in your browser and never uploaded.