For our Cityscape Pro members: We've added a new Property Finder map that shows properties that have delinquent taxes for the 2018 and earlier tax years. A tax sale will occur in May 2020 (this is different than the biannual scavenger sale).
We will soon be adding a lookup tool that will enable users to see if a given address or PIN is listed in the tax sale. The Cook County Treasurer, which manages the tax sale, has their own lookup tool.