In my thesis I present the designing and developing process of a web-based application based on a project defined by the Distinction Software Development Services Limited. I examine the HTML5 technology, its common used new features and possibilities, the jQuery library, the CSS3 styling language, the structure and techniques of development of web-based applications and the problems and reasons of browser incompatibilities. I demonstrate the designing and implementation process of a client-side web-based application on model, user interaction,interface and design level. I introduce the design decisions and their reasons. I specify the problems occurred during the development and their solutions. I mention the modern developing methods and environments. This document also includes the documentation of the measurement on the page, able for comparing the different web-technologies. I conclude my essay by summarizing the experiences and drawing up the possibilities and direction of the future development.