Zillow receives all open house information from feed sources, such as your local MLS. If Zillow can receive Open House data from your listing service, the open house date and times will be displayed alongside the MLS listing info on the Zillow property page. The open house must be flagged as Public and In-person to appear on Zillow’s pages.
If Zillow does not receive Open House data from your listing service, you are unable to add an open house date to the Zillow property page.