Build app/web multiplatform (iOS, Android) and backend with PHP, MySQL. HIHGLY CUSTOMIZABLE

We need to build a multiplatform app (iOS, Android), a web page and a web administration page. The app is basically a communication service between companies and employers. Therefore the used data is private and confidential between sender and receiver. The programmer must assure the security and the backup of the data. There are different levels with different privileges, please see image 1. Preferred languages are PHP and MySQL, but the programmer can recommend other languages and methods if security is increased. The app will be highly customizable. That means that some of the variables (color, icons, moduls, text…) will be parametric, so that administrator can customize the app for every user. (See image 2) Graphic design is very simple. As a graphic template we could say the app/web will look pretty much like “freelancer” app/web. There are different modules that will be explained in a detailed guided. Please read carefully this description, and add the word "MOSCA" before you make a quotation. That will tell us that at least you read our description. Please, fulfill attached file with further questions you might have and final price. We don't have time to read all your portfolio, please send only related apps. Main characteristics in order to make your best offer are: 1.- Social media access and share options. 2.- Online chat between user/user and user/admin. 3.- File sharing between user/admin. 4.- Push messages from admin. 5.- Highly customizable app from admin side (Colors, icons, text, etc..) 6.- Languages: 5. All text in all languages will be provided. In the admin side there must be a modul to include new languages transcriptions in text mode. 7.- Database. The project is mainly a data exchanging and sharing program between users and admins. So a well structured and safe database will be very important. It is highly appreciated when the bidder provides solutions that will increase the security and availability of the data. 8.- Graphics are very simple. Icons and pictures will be provided. 9.- Maximum time delivery is 60 days. There is a very detailed guided that will be provided and also fluent communication between programmer and designer is required. Please DO NOT bid if you don't have a proven background in developing this kind of apps.