The app, supplied by New York-based Bytemark, lets riders purchase and store train tickets on their smartphones. It is available for both Apple iOS and Android devices.
Train schedules, arrival times, and a system map are also available, Bytemark said.
"Bytemark is excited to partner with NICTD to launch the South Shore App," said Bytemark CEO Micah Bergdale. "Mobile ticketing is becoming a standard for transit systems around the world, and we are pleased to provide our flexible and secure mobile ticketing solution to commuters across Indiana and Illinois."
Said NICTD General Manager Gerald Hanas, "We are happy to offer a more convenient method for passengers to purchase their tickets. We anticipate that mobile ticketing technology will become more popular as passengers discover just how easy it is to use."