The purpose of this thesis is to develop a deeper understanding of the potential benefits of using an open-source library when building a design system. The thesis uses a research through design approach in three steps; (1) identifying what a design system contains and the possible advantages of using one. (2) Building a design system based on an open-source library. (3) Evaluate how the new design system performs by comparing its performance to the possible advantages identified in step (1). In the result chapter, the design system is presented, and the design is motivated based on the brand identity. The discussion evaluates what pros and cons it might bring to use an open-source design system compared to the general advantages of design systems mentioned in the literature. It also evaluates the process and provides knowledge for anyone wanting to use an open-source design system. In the conclusion, this thesis argues that itis useful and time-saving for any company to use an open-source library when it comes to simpleand often recurring components. However, since every application solves specific problems, the creation of unique components is inevitable. Using already designed components could also limit the ideation process since the designer already have a toolkit to use when solving problems.