RET is a free iPhone app developed by Rotterdamse Elektrische Tram N.V. afgekort R.E.T. N.V. It serves as a comprehensive tool for accessing real-time public transport information in Rotterdam. Users can check the latest departure times, view their travel history, purchase barcode tickets, and receive push notifications for disruptions on their favorite lines or stops.

The app features a travel planner that allows users to navigate through the Netherlands using various modes of public transportation, including buses, trams, metros, and trains. Additionally, users can connect their payment cards to track their travel expenses and access a range of shared mobility options in the vicinity.