Getting Started Overview Get started with the Fitbit Software Development Kit (SDK), you can quickly create apps and clock faces for Fitbit OS 5 devices, such as Fitbit Versa 3 and Fitbit Sense, or older Fitbit OS 4 devices, such as Fitbit Versa, Versa Lite, and Versa 2. What You’ll Need Before you get started, you'll need the following prerequisites to develop apps or clock faces with the Fitbit