This paper is a literature study with an additional empirical approach to research how to improve user experience in data visualization web applications. This research has been conducted in collaboration with Caretia AB to improve their current data visualization tool. The research studies previous research on the topics of UI design, user experience, visual complexity and user interaction in the attempt to discover what areas of design and intuitivity that improves the user experiences in these kinds of tools. The findings were then tested together with Caretia through a proof-of-concept prototype application which was implemented with said findings. The conclusion of the results is that mapping ontology groups and prior experience as well as reducing visual overload are effective ways of improving intuitivity and user experience.