Plone, content management software for the web, is built using the programming language Python and Zope, a web application server and database. All of these are open source software, developed by global online communities. Plone is an ideal platform for writing educational software, because user account functionality is built-in, and because basic functionality for adding web pages, uploading images and files, and data querying is robust. Python-based add-on (or "plug-in") software is developed on the filesystem, and may tap into a rich set of standard and scientific software libraries for Python. For meteorology and related sciences, the use of Python libraries to produce dynamic graphics for maps and charts is an ideal fit. There are also facilities for building object-based mapping applications for storing observation data and for presentation on dynamic online maps. The underlying Zope object database is robust for most tasks, but connections to backend databases, such as PostgreSQL, and to GIS server applications can be installed as well. Developing custom software involves following the examples, recipes, and API guidelines for Archetypes, the underlying programming facility for writing applications that plug into the Plone/Zope system.