TTVStreamerTool comes with a overlay host that runs in the background and can be accessed under `http://localhost:8090`.
By default TTVST only comes with a music overlay with which you can play a youtube playlist and a countdown overlay. More overlays can be added via addons, that you can create yourself.
Other than a lot of other overlay provider these overlays can be controlled with Hotkeys or HTTP request. This makes them highly customizable, controllable through different methods and automatable.