Property speculators own nearly 20 percent of all property in Detroit. The parcels caught up in this web of speculation are spread across the city and come in a variety of forms. At their worst these owners are buying and selling houses that rapidly decline into vacant and abandoned shells. Too often neighborhoods and the public are forced to bare the cost of these activities from the daily reality of physical deterioration, to declining property values, and increasingly costly demolitions. The recent mortgage crisis created a large inventory for speculation while most government response at the federal, state and local level is dedicated demolishing the aftermath of these activities. What is not addressed is the production and producers of these conditions. This project demonstrates the scope and actors producing the landscapes of vacancy and abandonment in Detroit and provides a strategic instrument for residents attempting to challenge speculative activity in their neighborhood. Property praxis is a data and design collective. All work is open source and freely available to those interested in developing similar tools in their cities.