Wix Bookings uses the IANA Time Zone Database as the single source of truth for all time zone calculations, including daylight saving time transitions. External databases may receive IANA updates at different times, and Wix doesn't reconcile those differences.
A site's time zone is determined by the timezone field in Get Site Properties, which reflects the primary address set in the site dashboard. Only 1 time zone is supported per site. When a site has locations across multiple time zones, Wix Bookings always uses the primary address time zone.
If a site's primary address changes to a different time zone:
08:00 in New York moves to 08:00 in Seattle, and the UTC value updates accordingly. Booked customers receive a notification about the change. Staff working hours follow the same rule: they retain their local time in the new time zone and Wix updates the UTC values.To return available slots in a customer's local time zone, pass the customer's IANA time zone string in the timeZone field when calling List Availability Time Slots.
For example, a customer in New York browsing a site based in Frankfurt:
The response includes localStartDate and localEndDate values in America/New_York.
Note: Wix ignores any UTC offset in fromLocalDate or toLocalDate when you set a time zone. Wix treats both dates as local time in the specified time zone.
A confirmed booking stores time in 2 forms. The top-level startDate and endDate fields are UTC timestamps, used for backend filtering. To display a booking in the customer's time zone, use the local time strings bookedEntity.slot.startDate and bookedEntity.slot.endDate together with bookedEntity.slot.timezone. Wix sets this time zone to match the one the customer saw when browsing availability, and it remains fixed for the lifetime of the booking.
To display the booking in a different time zone, convert from the UTC startDate and endDate values.
When filtering bookings by date in Query Extended Bookings, date filters such as startDate, endDate, and createdDate must use UTC time. This is the opposite of the Time Slots V2 API, which accepts local dates paired with a time zone string.
List Availability Time Slots automatically handles DST transitions.
Recurring sessions and working hours: Recurring class and course sessions and staff working hours always retain their local time through DST transitions. A class created at 09:00 America/New_York remains at 09:00 after the DST change. Wix updates the UTC values automatically.
Clock springs forward: If a requested local time doesn't exist because clocks skipped forward, Wix advances the time to the next valid local time. For example, if clocks in Santiago, Chile, jump from 00:00 to 01:00, a fromLocalDate of 00:00:01 is automatically shifted to 01:00:01.
Clock falls back: If a requested local time occurs twice because clocks fell back, Wix uses the 1st occurrence, before the transition. The 2nd occurrence (the same local time at the later UTC offset) isn't available as a separate bookable slot. To avoid ambiguity in queries, use UTC-based filtering instead.