Within a few years the idea of open data has spread throughout Europe and produced extensive changes especially in thinking about governmental data and how it can be used for public and private purposes. This has also led to a fractured landscape of open data resources, making it challenging to gain an overview. Even on a national level there is an unconstrained growth of regional open data repositories. These circumstances cause extensive problems for policy makers, institutions and NGOs, to build up efficient and sustainable open data strategies. Further, identifying gaps in and opportunities for open data publishing is almost impossible. Finally, on a pan-European level there is a lack of analysis on this topic which hinders the large-scale reuse of open data.OpenDataMonitor provides the possibility to gain an overview of available open data resources and undertake analysis and visualisation of existing data catalogues using innovative technologies. By creating a highly extensible and customizable harvesting framework, metadata from diverse open data sources will be collected. Through harmonization of the harvested metadata, the gathered information can be structured and processed. Scalable analytical and visualisation methods will allow the end users to learn more about the composition of regional, national or pan-European open data repositories. For example the aggregation of catalogues of one region or country can be easily visualised to draw an exact picture of the open data situation and allow comparison to other areas. Analysing and visualising metadata will reveal hidden potential and essential insights from existing resources and identify gaps where additional open data are needed.To guarantee the availability, usage and reuse of the created plugins and components during the OpenDataMonitor project, established open source software like CKAN will be adopted and extended. The research outcomes and technical developments will be combined in a demonstration platform, integrated in third-party sites and will be distributed to the open data community to maximise impact.