So what is this?

The NYC Landlord Lookup portal is an experimental tool created to provide easy access to various information sources in the NYC real estate data ecosystem (some well known, others not well-known). It's a project run by volunteers, and ultimately intended to be open source.

Features and Scope

It doesn't do a whole lot, at present -- but what it does do, it tries to do very accurately. The primary area of focus is on what we call the "backbone" (making sense of, and smoothing over gaps in the City's somewhat archaic numbering system for tax lots and buildings), and on (rigorously) identifying current property ownership. Importantly, it aims to capture every taxlot and building in the system, and to work on any (reasonably) valid address or property identifier you might wish to feed it in the search bar.

And the second area of focus is on identifying properties that have some form of rent stabilization, or are otherwise enrolled with the city as "affordable". This is somewhat tricky (especially in regard to identifying stabilized properties), because while it's easy to tell if a building might be stabilized, to tell whether it actually is stabilized you have to cross-check various obscure datasets. So far as we know, this the only search portal that provides this category of information.

And finally, we put it all on a map. Because everyone likes looking at maps.


Currently the portal makes use of some 25+ datasets, taken from various city agencies. We'll be providing a detailed list in the near future, but special credit and thanks go to:

Usage + Caveats

By this point most address searches seem to go through, and when they go through they're quite accurate (if in fact they describe a valid address). That said we're currently entirely dependent on the City's Geoclient API to do the actual address-to-BBL conversion -- which, while generally quite good, has been seen to fail on valid addresses, occasionally.

And when it does identify a property, there are still various glitches in the city's numbering system -- particularly as applies to recently built or demolished buildings, and recently registered condominium projects. Statistically speaking these "holes" are quite rare, but because they apply to newer development projects (that you're more likely to do searches on), they appear often enough. So this is one of the areas we're currently working on smoothing over at the data aggregation level.

Also, it's not mobile-optimized. Sorry, haven't had time yet. We'll get to it, though.