Spatial Data Infrastructures still focus geodata discovery and visualization. Web platforms for publishing, sharing and documenting geospatial algorithms are equally important, but do hardly exist. The Geoprocessing Appstore, a Web-platform respectively portal, provides a software solution for current algorithm discovery and access problems. It allows users to publish, search and download implementations of geospatial algorithms. Supplementary to the algorithm management and discovery components, the Geoprocessing Appstore comprises a knowledge platform to manage and cite semantic descriptions of geoprocessing functionality. Further, the Appstore’s algorithm sandbox enables to test and execute published algorithms. The implementation of the Geoprocessing Appstore bases on various Open Source software frameworks and uses standard interfaces to ensure interoperability and integration into existing Spatial Data Infrastructures or software components.