Launching the app, South Eastern general manager A K Goel said, "This will immensely help passengers by saving time and the trouble of standing in queue."
SER introduced the facility of unreserved ticket booking through GPS-enabled smart phones, which can be done from open space beyond 20 metres and within two kms from station or railway tracks.
The facility will cover single/return journey, platform tickets and season tickets, SER sources said.
Cancellation of tickets booked through the mobile app would not be allowed, the sources said.