I use Restyaboard for this Kanban approach. It’s a productivity and management tool specifically built around a Kanban-style workflow. It is widely used as a great free tool for Project Planning and Management, Task Management, CRM, Bug tracking. I love it!
I too moved from Trello when they announced their restrictions. I moved to Restyaboard, a very good free Trello alternative. Migration from Trello to Restyaboard is easy without losing my data.