Existing mobile app with source codes have standard social features

We want to look for Existing mobile apps with source codes and then hire mobile developers to modify and customize it to fit our needs. If you have or built some of apps with features overlapping what we need, please give details. The app we want to built includes those features: 1. standard account login, account creation. 2. user can create profiles, filling out some personal information and a profile picture. 3. user can create an ad (like cg list), fill out form and description of the ad. (different categories) 4. Other users can see ads posted by users nearby (geolocation) 5. Other users can choose to respond to ads by directly start chat with ad posters. 6. users can track those ads he posted and those he responded. 7. It's free to post ads, but a membership subscription is needed to respond to ad. 8. membership subscription payment and user status managment 9. users can follow other users or ad category to receive push notifications of new ad 10. build viral features allow user to share an ad or the app, invite friends. 11. user can set settings and personal preferences. It's an app allows users to post ad and respond to ad and chat with each other about details. It involves geolocation tracking (user can see nearby ads), push notification (when new ad fit criteria are posted), Chat with each other, Membership to restrict ability to respond to ad. In stead of building the ad from scratch, we are looking for apps with similar standard features to modify and customize. If you have existing app can be used for this purpose, please provide details including technology behind it, the features included, ideally provide a demo. If you are the developer of the existing app, we will consider hiring you to do the modification work. Your bid price is for giving the source codes of the app. Depends on the feature availability, the price for the app varies. Customization work will be paid additionally.