A system for organizing volunteer work?

Question

Project management

Hey everyone!
Are there services/programs/systems for organizing volunteer work?
The difference between such systems and conventional project management systems is that there is not always a strict hierarchy. We need the possibility of self-organization of a group of users, the functionality of joint decision-making (voting / consensus), the ability to function in a “flat” hierarchy, and other specific points.
It is desirable that the system can be installed on your server and not depend on the eternal inconstancy of third-party services.
I think you can even use Redmine, but there will be a lot missing.

Answer 1

Trello plus google docs.

Answer 2

There seems to be no Open Atrium
voting out of the box, but any necessary functions are added by third-party modules