The Biodiversity Exploratory Information System (BExIS) is the data repository and information exchange platform of the Biodiversity Exploratories project. The Biodiversity Exploratories started in 2006 and is funded by the German Science Foundation (DFG) as a long-term, interdisciplinary open research platform. The goal is to advance biodiversity research in Germany and further the understanding of the relationship between biodiversity of different taxa and levels, the role of land use and management for biodiversity, and the role of biodiversity for ecosystem processes. At present 40 projects with 300 researchers work on 1000 research plots of two landuse types in three regions in Germany. The interchange of data among projects is considered crucial for the success of the project. The diversity among the involved projects is mirrored by the diversity of file formats, -syntax and, semantics. BExIS supports file formats common among its researchers and allows data ingestion of flexible syntax, determined in collaboration with all field researchers. BExIS has a web-based interface to a platform for storage and management of all project data in a database. It has a fine grained user and rights management and offers upload, update, and online edit of data. BExIS supports different structured data types and unstructured data. Support of flexible data syntax is ensured by use of XML based metadata schemas and datastructure mapping. BExIS provides further project desired functionalities, e.g. to organize and document field work, for visualising and editing common data on maps, and provides the use of statistical analysis also for online merged data sets.