Do I have to have an activity tracker? Or, is this supplied by KrowdFit?

If you already own a Fitbit or other tracking device you do not have to buy one.  You can join KrowdFit as a member and connect your fitness tracker to your account.

If you don’t have a fitness tracker you can connect your Android or iOS device by using their respective health tools. Apple Health is available for iOS and Google Fit is available for Android.