Currently, mobile devices are the most popular pervasive computing devices, and they are becoming the primary way for accessing Internet. Battery is a critical resource in such personal computing gadgets, network communications being one of the primary energy consuming activities in any mobile app. Indeed, as web-based communication is the most used explicitly or implicitly by mobile devices, HTTP-based traffic is the most power demanding one. So, mobile web developers should be aware of how much energy demands the different web-based communication alternatives. e goal of this paper is to measure and compare the energy consumption of three asynchronous HTTP-based methods in mobile devices in different browsers. Our experiments focus on three HTTP-based asynchronous communication models that allow a web server to push data to a client browser through a HTTP/1.1 interaction: Polling, Long Polling, and WebSockets. e resulted measurements are then analysed to get more accurate understanding of the impact of the selected method, and the mobile browser, in the energy consumption of the asynchronous HTTP-based communication. e utility of these experiments is to show developers what are the factors and settings that mostly influence the energy consumption when different web-based asynchronous communication methods are used, helping them to choose the most beneficial solution if possible. With this information, mobile web developers should be able to reduce the power consumption of the front-end of web applications for mobile devices, just selecting and configuring the best asynchronous method or mobile browser, improving the performance of HTTP-based communication in terms of energy demand.