I am the Agility Master for our Kanban Team and in our Retrospectives, we would like to follow some basic approach, where we collect, group and vote on topics to the classic „What went well“, etc.
Now the first part is easy. There are tons of tools, that help you here.
Coming to the hard part: We also would like to do root cause analysis for two to three voted groups and I am unable to find any tool, which has it all.
We are helping ourselves currently with MS Whiteboard, which works for us, but it could be better.