Online civic engagement platforms accessed via desktops or mobile devices can provide new opportunities for the public to express views and insights, consider the views of others, assist in identifying innovative ideas and new approaches to public policy issues, and directly engage with elected leaders. Existing platforms vary widely in their approaches to: assessment, engagement, ideation, evaluation, and deliberation. We consider three online platforms: the Living Voters Guide, including its earlier iterations Consider.it and Reflect; the Open Town Hall; and the California Report Card. We compare them using the International Association of Public Participation’s “Spectrum of Public Participation” framework. Using a 10-point scale, we evaluate the user interface of each platform in terms of how well it supports the Spectrum’s levels of civic engagement (inform, consult, involve, collaborate, and empower). Results suggest how user interface design affects civic engagement and suggest opportunities for future work