- If you are on Slack, Kyber is your best choice. You can use it for personal productivity, combining todos, reminders and calendars in a single view. You can also use it to assign tasks directly to teammates or in a channel. Each new task is added to a shared list between you and the other user if in a DM or with the entire channel if in a channel. It's fully native on Slack, but there is also an iOS app.