marketplace App

I am looking for a developer to build a marketplace app for me. The app should have buy/sell functionality, chat messaging, and ratings/reviews. I would like the app to be available on both iOS and Android platforms. The target audience for the app is the general public. The ideal developer for this project should have experience in developing marketplaces and be proficient in both iOS and Android app development. This is app like OfferUp and Groupon combined