Discover Apps gallery (Delevoper Preview)

With the Public Developer Preview as of August 25, 2017, a new gallery to discover apps is available. Before you can use this feature, you need to switch to the ‘Developer preview”. Please read this post how you can do it. After switching you will see a new icon ‘Get apps” in the left pane.
The gallery provides a listing of all apps available in Microsoft Teams. It includes bots, tabs, connectors and compose extensions.