Our API directory now includes 40 real estate APIs. The newest is the XWeb Real Estate API. The most popular, in terms of mashups, is the Zillow API. We list 28 Zillow mashups. Below you’ll find some more stats from the directory, including the entire list of real estate APIs.
RentRent.org has announced the creation of an API that searches local Craigslist entries for rental properties including apartments and houses. This gives developers the ability to integrate rental searches with mapping applications and APIs (our RentRent API profile has details). [Note that RentRent.org is not associated with Craigslist.org.]