Listings from HUD, VA, FDIC, IRS

Army Corp of Engineers, US Customs,

U.S. Marshals, Dept of Agriculture 

Multiple Listi​ng Service 

The most reliable, up to date

local listings

The most reliable, up to date 

nationwide listings

There are thousands of Real Estate web sites 
All the information they have comes from these.
Most 3rd party sites are not real estate sites but advertising sites

and do not update regularly