I used Trello years ago but I don’t want to use proprietary software anymore. So I found this one, which seams pretty similar to any other Kanban board website : Taiga
I will see if I really use it or if I stay with my beloved pens and papers 
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Hi. I’m not using these tools for customer relationship management so I don’t know if I can help you. But for project management only, Taiga is more than enough: free, open source and with a wide range of tools: Scrum, Kanban, Wiki, issue tracking and so on 