With Free Market you can download paid apps for free without paying a cent! Developers when submit their apps to the Store, can choose one price for all countries or different prices for different countries with their own reasons. There are about 200 supported countries and there is a chance an app be free in one of these countries.
With Free Market, you can select a paid app and it will search among all available markets to find a free version in a country. Then you can easily change region of your phone to that country in settings and download the paid app for free!
Note: some developers don’t provide a free version in any country, but you still can find free versions of some other valuable apps.
App itself is completely free! without any ads!. Give it a try.