Tizen Studio provides everything you need to develop apps for Tizen, including the IDE and the SDK tools.
Tizen Extension SDK
The Extension SDK provides new IDE functionalities to request and register certificates, Samsung Extension API to provide advanced access to the Samsung device's platform capabilities, and includes Web Device API and Native API.
Since v1.2.0, In-App Purchase API is provided to purchase items and get item list from Samsung Galaxy Apps and Remote AppControl API, which interacts with remote applications installed on the host device.
Samsung Accessory SDK
Those who develop Galaxy Watch Companion type applications need this SDK. Accessory SDK allows you to connect Galaxy Watch devices to host devices. With Accessory SDK, you can define a new service between the Galaxy Watch and host device, enabling you to use the various host device functions from the Galaxy Watch device.