With its oceanic climate with moderate summers and mild winters in combination with a highly organized infrastructure, farming has traditionally been very intensive in Denmark. The cultivated land constitutes 26,000 km² out of a total of 43,000 km². Most of the arable land is used for intensive plant production with a high level of mechanization and management practices. For more than three decades The Knowledge Centre for Agriculture (KCA) has developed and implemented ICT Farm Management Information Systems (FMIS) for planning and documentation of all aspects of crop production. Today, updated field specific information on field size, soil type, crops, varieties, soil tillage, sowing, fertilization, pesticide usage etc. is now hosted in the GIS-based FMIS, Mark Online covering more than 80% of the arable land. A centralized Microsoft SQL data base forms the core base for all the information. Based on a MS .NET framework a number of multi-tier client-server applications have been developed. Most of the desk top applications consist of relative thick clients based on Win forms, whereas HTML5 apps and Android/IOS native apps are used for the mobile platform. Data exchange between the clients and server are based on a web service layer using data compression to improve performance. Farmers are one of the two primary target groups. Local agricultural advisors working on behalf of farmers not having their own software is the other primary target group. Nonetheless, both groups are mainly focusing on field record planning, decision making and documentation. Data is transferred between the Mark Online system and the authorities by XML-based web services or ordinary file upload to official websites. The Open Geospatial Consortium’s Web Feature Service (WFS) provides another interface allowing requests for geospatial features, which is used between Mark Online and external GIS.