AttendanceBot for slack is the simplest way to know when someone is on leave or working from home. Just dm @attendancebot messages like 'sick today' or 'on leave from 11-08 to 14-08' or 'WFH tomorrow' and it will record it. If you have a manager, it will send your leave request for approval and notify you on its status. You can also view the leave snapshots of your team or any team member. Its been designed to take note of leaves and get out of the way.