Decidim Helsinki is a participatory democracy system, that is built on top of the Decidim platform. The software supports various ways of bottom-up participation online.

Citizens can for example submit proposals on city development, discuss them and improve upon them collaboratively. Citizens are able to enter into dialogue with city planning experts who review the proposals and estimate their implementation costs. Votes can eventually be cast on which proposals are to be implemented and the implementation can be monitored online.

The system also supports face-to-face participation, with functions like event registration, meeting agendas and minute sharing

Decidim Helsinki is currently being used to run pilot websites, including one for citywide participatory budgeting. 

Decidim Helsinki is based on Decidim, a free and open source participatory democracy platform written in Ruby on Rails. The Decidim project was originally kick-started and funded by the Barcelona City Council, but it is now being used by dozens of cities and organizations across Europe.