Loomiohttps://www.loomio.org/ an online platform designed for group decision-making and collaboration. Users can create proposals, discuss them, and vote on decisions in a transparent and inclusive manner.
Decidimhttps://decidim.org/ a free, open-source platform for participatory democracy that allows users to propose, debate, and vote on decisions within a community.
Consulhttps://consulproject.org/en/ an open-source platform for citizen participation, which can be used for various purposes like public consultations, participatory budgeting, and collaborative legislation.
DemocracyOShttps://democracyos.org/ an open-source platform that provides tools for online voting, discussion, and debate on various topics.
IdeaScalehttps://ideascale.com/ a crowdsourcing platform that allows users to submit, vote on, and discuss ideas, proposals, and innovations.
Nestrhttp://www.nestr.io a tool for organizing holocratic circles and creating requests between autonomous organizational departments.
Polishttps://pol.is/home is interesting for computational democracy at large scale. you can use this tool to gather large amounts of data about what groups of people think in their own words.