About This Tool

This tool generates UUID v7 identifiers from the current UTC time (milliseconds) so they remain sortable by time. The selected time source and "time to use" directly affect the timestamp, matching the preview exactly. By specification, UUID v7 always uses the corresponding UTC timestamp even if you choose a time zone. All processing happens in the browser (no data is sent).

How to use

1. In Time check, choose Local / IANA / Fixed offset (the defaults are usually fine).
2. In Time to use, pick Current time or Specified datetime. When specifying, enter YYYY-MM-DDTHH:MM[:SS[.mmm]]; the preview and generation use that value.
3. When Specified datetime is selected, the value is interpreted in the time zone chosen in Time check and converted to UTC for generation.
4. Set Quantity, toggle Monotonic generation if needed, then press Generate. Results appear line by line.

Additional notes

• The preview shows the current UTC time and the local time for the selected source. The previewed timestamp is used as-is when you generate.
• IANA time zones resolve offsets with daylight-saving time (DST) taken into account via iterative adjustment.
• The output area is read-only; use the buttons to copy or clear it.
• Each run re-initializes the randomness so repeated clicks produce fresh sequences even with identical settings.

Cautions

• The UUID v7 timestamp is always UTC epoch milliseconds; time zones affect only the display. When generating with the current time, switching zones does not change the timestamp bits.
• Only when Specified datetime is chosen is the entered wall-clock time converted (using the selected source) and applied to the UUID timestamp.
• Monotonic ON: increments the trailing bits within the same millisecond. OFF: randomness is fully reshuffled.

What is UUID v7?

UUID v7 stores the Unix epoch milliseconds in the first 48 bits, followed by the 4-bit version (7), 12 + 62 bits of randomness, and a 2-bit variant (10). It balances chronological ordering with uniqueness.