PeriMetro is a free Android application developed by Konstantinos Reppas for social and communication purposes. It aims to bring anonymous commuters of the metro together for constructive discussions and exchange of opinions, as well as to inform them about incidents that require everyone's attention. The creators of the application do not take any responsibility for the content of the conversations and encourage all passengers to travel legally and safely.

One of the main features of PeriMetro is the notification system for strikes, keeping commuters up to date with any disruptions to their journeys. Additionally, the new "Saw You" section allows users to report sightings of people they have seen on their commutes. The app is easy to use and provides a platform for commuters to connect with each other anonymously while sharing their thoughts and experiences.