Full-stack development of a simple social media app

Hi! I need a full-stack software developer who will do the front and back-end development for an Android and an iOS application as well as the User Interface design. We may in the future need a web interface as well (as a second project), so all the technology used should support easily adding a web interface. The user interface should be designed to allow the use of different languages (English / Turkish / German at first). App users need to create an account and login to access the application Application will tag the gps location and relate the gps location with predefined locations. Application will list the recent check-ins as well as the most popular users at the current location. So, if a user is near a location he/she will be able to see the check-ins only at that location. When the user leaves the location, he/she will no longer be able to see the check-ins at that location. Everybody will be able to see everybody else (as long as the above location requirement is satisfied). All the code developed should be shared with us and we will be the owner of the developed code. The back-end should be scalable to thousands of active users and support the use of Amazon Web Services and/or similar cloud computing resources. App should be able to pass the App store requirements. Please share your proposal including the technologies you plan to use for each layer. User interface / application / server communications / server management / database etc as well the time and cost. Greetings.