My Tennis Contract allows a group of tennis players to share and view a schedule, usually weekly, of who plays on what date and who brings the tennis balls. That sounds simple until you have more than 4 players sharing a tennis court and have the need for substitutions where typically emails go out for a sub, someone takes it, and the schedule is updated in a hard-to-find spreadsheet. My Tennis Contract puts this schedule on your phone, with real-time notifications on sub requests, updates to the schedule, and push notification reminders to the players the day of or day before the session.