RahuKaal app is a very useful utility for Hindus. You can see the rahu kaalam today and the next seven days based on your current locations without any input from you. App automatically calculates the rahu times for you.
App also sends you notifications to remind you when the rahu kalam starts and ends. You dont have to run and open the app to know the times. All you have to do is install the app and let it do the work for you.