Which platform is being used here?
This platform is based on the free open source software «Decidim», which is processed and operated by the City of Barcelona. Aside from the «Quartieridee», various cities such as Helsinki, Lille or Mexico City also make use of this platform. The platform has been adapted to the project-specific needs for the «Quartieridee» Wipkingen.
You can find further information on this adaptation of Decidim in this blog-post by Urban Equipe.