e-Legion team has developed a mobile tool for the Burger King clients in Russia. The app allows to make a preorder and save the time — there is no need to stand in queues, you can simply go to the delivery zone and tell your order number.The scope of our work includes analytics, prototyping and design, development, QA, and technical support and further app development.The main task was to create a convenient and safe tool for guests of the Burger King restaurant network in Russia which will allow users to create a pending order and pay for it, be aware of special offers, and find the nearest restaurant in online and offline modes.We have created a flexible utility for loading images based on Glide. We have also implemented effective data caching from the application side which allows to save traffic to users and significantly reduce the load on the server part.We created a flexible network exchange dealers with the central server which metered the load on the network depending on the current order conditions and saved the traffic and battery of the mobile device.Users pay for the order directly in the application. Therefore, we have taken care of protecting user data both inside the application and in communication channels with the server. We paid attention to the protection of transaction purchases from fake requests and external attempts to deceive payment systems bypassing the application.