This paper introduces the utilization of open standards and open source software for visualization and distribution of geospatial environmental science data at the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC). The ORNL DAAC is one of the NASA Earth Observing System Data and Information System (EOSDIS) data centers. A big challenge for the ORNL DAAC (https://daac.ornl.gov) is to efficiently manage over a thousand heterogeneous environmental data, collected through field campaigns, aircraft/satellite observations, and model simulations. ORNL DAAC also has to provide tools to easily find, visualize, and access the heterogeneous data. To address this challenge, the ORNL DAAC has leveraged Open Geospatial Consortium (OGC) standards and open source software to develop the Spatial Data Access Tool (SDAT, https://webmap.ornl.gov/ogc). SDAT is a suite of open standards-based web mapping, subsetting, and transformation services and applications that allow users to visualize and download geospatial data in customized spatial/temporal extents, formats, and projections. The open source MapServer/Geospatial Data Abstraction Library (GDAL) powers the backend OGC Web services of SDAT. Open source Javascript libraries, including OpenLayers, GeoExt, and proj4js, were used to create the SDAT Web User Interface and MapWidget, a light-weight Javascript library that allows SDAT visualization to be easily embedded on any webpage. SDAT also provides KML files to enable interactive data visualization in the popular Google Earth application or any KML-compatible client. SDAT provides a common framework and standard service interfaces for ORNL DAAC data holdings. SDAT user interface hides their heterogeneity from end users, and promotes their usage. SDAT facilitates integration of ORNL DAAC data resources with other related data systems. In 2016, SDAT served more than 2 million mapping requests and 72 thousand customized data downloads from over 2500 distinct data users.