In recent years, governments have emerged as the biggest data holders, producing extensive amounts of historical and contemporary data. The demand for transparency has led to the rise of Open Government Data (OGD): data produced or collected by state bodies made freely accessible, modifiable, shareable, and usable by anyone for any purpose with minimal restrictions. OGD is seen as a foundation for economic growth, competitiveness, innovation, job creation, and societal progress. For example, the total direct economic benefits of OGD in the EU and UK are forecast to increase from €52 billion in 2018 to €194 billion in 2030. To maximise these benefits, governments have adopted supply-driven strategies focused on producing large volumes of datasets, assuming greater supply will lead to greater use. OGD portals have been developed as central access points, but they often fail to meet users’ needs. In Switzerland, for instance, most respondents report that the national OGD portal does not meet their needs. This reflects a misalignment between supply and demand: large volumes of data lead to data pollution, while limited data literacy makes it harder for users to find and use relevant data. This thesis argues that OGD portals reveal cross-cutting issues across the OGD ecosystem — production, distribution, and use — that reinforce this misalignment. It examines the usability of the Swiss OGD portal and shows that poor usability can make data practically inaccessible, especially for users with limited technical skills who rely on the portal as their only access point. Improving usability is key to ensuring OGD strategies succeed in bridging the gap between supply and demand.