A digital decision aid for cancer screening can gather balanced information in one place and give individuals the opportunity to elucidate their knowledge, values and engage in shared decision-making. Research shows that ethnic minorities and individuals with various functional limitations participate in cancer screening to a lower extent, hence our ambition to make the decision aid as available and applicable as possible, regardless of end-users' traits. The aim was to describe the design and alpha phases of the development of a digital decision aid for CRC screening and tentative end-users' perceptions. Based on a scientific framework for development of decision aids, participants were recruited through multiple channels. The decision aid was evaluated in two steps, a paper version (design phase) and a website prototype (alpha phase), using the think-aloud approach. Data were rich with detailed suggestions for improvements of the decision aid and how it was perceived. A positive outlook on the decision aid was common. Certain words, wordings or visual features were considered difficult and worry or anxiety, related to the content, were expressed. The variation in the findings illustrates the challenges of decision aid development. Still, our findings emphasise the importance of designing a decision aid in co-creation with its end-users. Developing a digital decision aid is complex, why a well-established framework is essential. With the goal of an equal healthcare system, the inclusion of individuals with diverse backgrounds and functional limitations should not only be a fundamental aspect of all research, but a prerequisite.