MyChicago Bus Tracker app shows realtime bus times for CTA riders
If you know the stop number, you can write and call directly.
If you do not know the stop number, you can reach the names of the stops and make a selection by choosing your route.
You can save as many stops as you want.
The application uses CTA data to show realtime bus times, when the buses will arrive at the stop
It is not official Cta Bus Tracker app, but this app makes use of CTA API