The goal of diploma thesis aimed to create an online store with open source tools and perform an analysis of the quality of the user experience. The thesis is divided into four parts. In the first part, we researched and described different methods of creating online stores. Here, we focused mainly on software technologies that can be used to manage an online store. Based on this research, we decided on a specific approach to creating an online store, which is described in diploma thesis. In the second part, we focused on planning a concrete online store. We described the look and structure of the online store and its subpages. While designing the implementation of the online store, the explanation of certain topics and described the alternative options for implementation were expanded. The description in the field of hosting and security of online stores is especially extended. In the third part, we focused on the concrete way of implementing an online store. We described in more detail the steps in creating an online store which was created for the purpose of the thesis. The online store is available at: www.spletna-trgovina.eu. It is outlined in more detail which specific technologies are used and how they work together. The implementation of the home page, product page and category page are also explained in detail. The fourth part is mainly concentrated on the methods and reasons for testing the quality of software. We have named the current ways of analyzing the quality of the user experience. Later, we optimized the speed of the online store because this is essential for a high level of online store quality. A concrete case study is presented on an online store which we made for this dissertation. In this study, we analyzed the speed of online store operation before and after speed optimization. The concrete ways of optimizing the speed of the online store, which it is also actually implemented, are described. We also presented potential ways to make the online store even more optimal, which we did not cover in the case study, but could also be used in a specific case. Then, with the survey questionnaire, we have further expanded the analysis of the quality of the user experience. The questions in the survey were mainly related to a specific online store, designed for the diploma thesis. The answers, gathered from the survey questions, helped us find out where in the online store there is still the possibility of improving and upgrading the online store.