I think a document-based collaboration tool works the best and collabee is definitely the one to look into. If you're tired of using Slack and getting interrupted too often, collabee is the one for you. I think we are living in an era where we feel like we should never turn off our notifications - whether in the personal realm or the professional - in order to stay on top of the things. Well, you can ACTUALLY snooze all the notifications in order to really focus on your tasks with this app. Everything that happens in between stays in the separate "Issue Updates" tab. It's so easy to find which update is directly related to you because they actually show you that you are mentioned or got assigned a task.