The commissioner for this thesis is Fingersoft, an Oulu-based company that was founded in 2012. The company operates in mobile gaming industry and has developed the very successful Hill Climb Racing. With all its titles combined, Fingersoft has bypassed a milestone of 1.5 billion combined installs across platforms. The area of study is digital marketing, and the research question goes as follows; How does the quality of ads impact the user experience? The idea came up during an internal meeting in a discussion on how ad-related operations can be optimized to improve the user experience. The aim of the project was to find out how much effect does the quality of ads have on user experience by comparing data gathered with A/B testing, which was a primary tool for conducting research. As the games developed by Fingersoft don’t necessarily require the user to spend any actual money to access the apps, ads play a significant role in gaining revenue. Therefore, optimizing ads operations is vital. As having balance between user experience and revenue is vital for a business and its profitability, the thesis will also touch on a sub-question of how the set of net- works associated with an application impact the overall performance. Theoretical base for the research was put together by exploring online resources such as articles and academic writings, as well as interviewing professionals working with ads, user experience and A/B testing. The test itself was run with a dedicated A/B testing tool. Results received from the experiment were not unambiguous and the benefit of changes applied in the test was not obvious. The analysis of outcomes indicated that Variant B should not necessarily be applied for the targeted audiences, but the results gained could be utilized for further testing and investigation regarding related issues. In coming to this conclusion, aspects considered were user experience related metrics and events and impacts on revenue – however, the development was not prominent on any scale. Which option seemed more profitable varied and depended on which metrics were under observation. Even though the hypothesis of high-tier audiences being more sensitive to low-quality content could not be proved either true or false and an answer to the research question was not clearly stated, the research was not useless by any means. As the purpose of ad monetization team at Fingersoft is to continuously seek new solutions and best practices to optimize their operations, finding answers to these types of questions is necessary. Now that the question has been widely explored, the process can be continued by asking more detailed questions about metrics and what impacts them.