FreeMarker is a template engine, a general purpose tool for generating text output based on templates, written in pure Java
FreeMarker is designed to generate HTML web pages, especially applications based on MVC pattern.
Although FreeMarker has some programming capabilities, it is usually a Java program to prepare the data to be displayed, a FreeMarker generates a page, and displays the prepared data through a template (as shown below)
FreeMarker is not a web application framework, but is suitable as a component of the web application framework.
FreeMarker has nothing to do with containers because it does not know about HTTP or Servlets; FreeMarker can also be applied to non-Web application environments