This new tool helps NYC tenants fight back against landlord violations

In an effort to demystify property ownership and management company networks across New York City,, a Brooklyn-based tenant advocacy nonprofit, launched a new tool today to help tenants easily obtain the information they need to deal with difficult landlords.

News Story (New York)

Alexandra Alexa
December 5, 2018

Tags: Housing: Landlord-Tenant

Organizations mentioned/involved:


The free tool, available at, aims to cut through some of the opaque practices of landlords, like the tendency to use a shell company or LLC to preserve their anonymity. The platform makes it possible to connect dots that are often hidden and will provide tenants, housing advocates, and local officials with the information to fight speculative behavior, harassment, and discrimination.

Who Owns What uses an algorithm built on NYC open data to conduct “property ownership mapping” that determines the buildings that a landlord or management company is associated with. It also includes data on code violations, evictions, and estimated changes in rent-regulated units in the building.

The primary source for this information comes from public data from Department of Housing Preservation and Development’s multiple dwelling registrations, which contains basic registration information for over 170,000 buildings in New York City.