A Java-based tool for determining if polygons require simplification before delivery to a mobile device using a Location-based Service (LBS) is described. Visualisation of vector-based spatial data on mobile devices is constrained by: small screen size; small data storage on the device; and potentially poor bandwidth connectivity. Our Java-based tool can download OpenStreetMap (OSM) XML data in real-time and calculate a number of shape complexity measures for each object in the data. From these measures an overall complexity score is calculated. If this complexity score is above a pre-defined threshold, specific to LBS, then the data is passed to a related software component which generalises (simplifies) the data. Our experimental results with actual OSM data confirm our expectations that some OSM polygon features can undergo simplification before delivery to an LBS with a significant reduction in the amount of data exchanged. The tool is completely web-based and runs free and open source software; all XML data processing is performed “on-the-fly” and the tool can be used for OpenStreetMap data anywhere in the world. This tool can become part of a very useful and efficient pre-processing step in the delivery of OSM data to mobile devices accessing LBS.