I am using irctc mobile app to book train tickets. With the older version of irctc app we can not able to book tatkal tickets and the works only non tatkal timings. Later got the updated version from the irctc with the new name irctc rail connect which is allowing tatkal tickets. It is also having the quick login access with the four digit pin, to available this feature we have register firstime opening the rail connect app.it quick and smooth with the tatkal also. I like this app to book train tickets.