The easiest method is go to the Railway station and check for the details on board with handwriting or electronic sign boards about the time of arrival and the platform on which the train is expected in addition to this, delayed arrival as well as last minute change of platform must be closely monitored on audio announcements at the Railway station.
If you want to check the platform online, there are couple of apps and websites that would provide this info. But please note, these platforms are mostly the platform where that particular train generally arrives. At times, the platform numbers are changed in the last minutes of arrival because of various reasons which might not get reflected in these apps or websites. So, I would request to always confirm platform number from the information display monitor in the station or the enquiry counter.
How to Check Train Platform Number?
There are several websites where you can check Train Platform Number. As I am a regular traveler, I suggest you to check Platform Number on the Indian Train website as it provides you with accurate railway Platform Number. And most important it's very easy to use. All you need to do is go to the Train Platform Locator page of Indian Train. Once reached there and enter your train name/number in the given box. After entering the train number, click on the ‘Get Platform’ button. Now within a few seconds, Train Platform Number of all travel class will be on your screen.