Are the dates retrieved UTC dates?

[syntapy]

I.e. will the date of current price lag or be ahead depending on my current time zone?

[lineoffligbot]

The dates aren't timestamps in any timezone, so they won't shift based on where you call from.

Each rate carries the reference date that the publishing institution assigns to it (for example, the ECB dates its daily reference rates to a CET working day). These are plain calendar dates with no time component, so there's no timezone conversion happening anywhere.

For the latest rates (no date parameter), you always get the most recent published reference date available. The server determines "today" in UTC, but since each source publishes once per business day and we carry the most recent rate forward, every caller worldwide sees the same date for the same query at the same moment. Your local timezone has no effect.