Android and IOS client-server application with registration and file upload and orders

Looking for a startup or good freelancer to develop an android and ios application with design and advise on back-end for an application based on client-server orders and file uploading. The application is not over complicated and the scope of work is clear. Main Features: 1-> IOS development, Android Development , Back-end Dev/Design/Consultancy 2-> Tool to access the orders by web from server (php?) -> Tool to access the files App Require features: 1) User Account registration and login (from side panel) 2) Order selection from panels + specification selection 3) User upload files reliably and securely accompanied the order 4) Camera overlay feature 5) Payment method * Lite Material design preferred Most important features: -> Responsiveness and animation smoothness is utmost importance in application. -> File Upload process is the number 1 priority in this application: It should be tailored and designed by the developers to offer best service and be forgiving for: closing application, connections slowness or problems Please attach portfolio and comment on your ability to handle file upload and give the best service for that as stated above.