Caltrain+

Caltrain+ is a Caltrain schedule and trip planning app that lets you quickly and easily figure out which train to take to get you from Station A to Station B. Additionally you can view full timetables, service alerts, and a system map all from within the app.
To use Caltrain+, simply select the station you want to depart from, the station you want to arrive at, and the timetable (Weekday or Weekend), and Caltrain+ will show you a complete list of every matching train you could take along with its number, service type (i.e. Local, Limited, or Baby Bullet), departure and arrival time, and trip duration. Optionally specify an “arrive by” time to filter the list of trains to only include those which will get you to your destination station before the specified time. You can also view the full list of scheduled stops for a particular train just by tapping on it.
Timetable information is provided by 511.org.