The materials flow mapping (MFM) app is designed to use the MFM-methodology to describe materials flows and assess their performance. The MFM-methodology is a result of ongoing research in supply chain management and is based on literature on what activities constitute a materials flow. A materials supply system is composed of the activities making the flow possible, the resources needed for the activities and the operators performing the activities. This app assists in doumenting and visualising materials flows in terms of materials handling activities, administrative activities, transportation activities and storage activities. Subsequent versions of the app will broaden the mapping and visaulisation capabilities. The MFM-methodology has many similarities with the commonly used Value Stream Mapping methodology (VSM). But whilst VSM focus on the value-adding activities, MFM focuses on describing and assessing the non-value-adding activities often disregarded by VSM.