Speaking or writing of political assemblies tends to evoke the action of people gathering to deliberate, or the spaces in which this deliberation might take place. One thing that is often overlooked, however, is the fact that these spaces can be digital. Online assemblies have become more widespread in recent years; from the first Web forums to civic technologies specifically designed to host collective political debates. As digital services affect our possibilities for political mobilization and participation, I will here attempt to define the qualities specific to online assemblies, and to identify several patterns and continuities in the design features of civic technologies offering online spaces for debate.