a serialization system that can produce and read XML and/or JSON representations of Django model instances a system for extending the capabilities of the template engine an interface to Python's built-in unit test framework Bundled applications The main Django distribution also bundles a number of applications in its "contrib" package, including: an extensible authentication system the dynamic administrative interface tools for generating RSS and Atom syndication feeds a "Sites" framework that allows one Django installation to run multiple websites, each with their own content and applications tools for generating Google Sitemaps built-in mitigation for cross-site request forgery, cross-site scripting, SQL injection, password cracking and other typical web attacks, most of them turned on by default a framework for creating GIS applications Extensibility Django's configuration system allows third party code to be plugged into a regular project, provided that it follows the reusable app conventions. More than 2500 packages are available to extend the framework's original behavior, providing solutions to issues the original tool didn't tackle: registration, search, API provision and consumption, CMS, etc. This extensibility is, however, mitigated by internal components' dependencies. While the Django philosophy implies loose coupling, the template filters and tags assume one engine implementation, and both the auth and admin bundled applications require the use of the internal ORM. None of these filters or bundled apps are mandatory to run a Django project, but reusable apps tend to depend on them, encouraging developers to keep using the official stack in order to benefit fully from the apps ecosystem. Server arrangements Django can be run in conjunction with Apache, Nginx using WSGI, Gunicorn, or Cherokee using flup (a Python module). Django also includes the ability to launch a FastCGI server, enabling use behind any web server which supports FastCGI, such as Lighttpd or Hiawatha. It is also possible to use other WSGI-compliant web servers. Django officially supports five database backends: PostgreSQL, MySQL, MariaDB, SQLite, and Oracle. Microsoft SQL Server can be used with django-mssql while similarly external backends exist for IBM Db2, SQL Anywhere and Firebird. There is a fork named django-nonrel, which supports NoSQL databases, such as MongoDB and Google App Engine's Datastore. Django may also be run in conjunction with Jython on any Java EE application server such as GlassFish or JBoss. In this case django-jython must be installed in order to provide JDBC drivers for database connectivity, which also can provide functionality to compile