Using the Slack Desktop application (not the web based version) of Slack, you can choose to have the application auto-start when you login. You can also choose to have the app minimize itself to your start bar.
File -> Preferences -> Advanced -> Other Options (at the bottom) -> Launch app on login
![](https://servicecenter.twu.edu/TDPortal/Images/Viewer?fileName=3c4680d2-b13f-4ba3-905c-b01d1036a3ac.PNG)
Download Desktop App Here: https://slack.com/downloads