FreeMarker VS Mustache.java

FreeMarker is a template engine, it allows to generate text output based on templates and dynamic data. It is similar to Mustache, Handlebars, Thymeleaf and other template engines. Templates are written in the FreeMarker Template Language (FTL) that supports conditional blocks, iterations, formatting, and many other capabilities.

Getting back to our two main technologies....we have implemented Keycloak as our Identification and Authorization Management system (IAM). However, as these things go, Keycloak has its own tech stack. One of the technologies, of course, is the language they used, which is Java. And being it is Java, they chose to use a templating engine called Freemarker.

The project I was working on was a website using Magnolia as their CMS. It uses the Freemarker templating engine under the hood. Essentially these are super-powered HTML files, which give you access to the CMS content. You can still use all of the HTML tags you want, including the

You can use Java for Backend and Frontend. A relative new kid on the block for Frontend is Qute. The general keyword you are searching for is Java Templating Engine. Specific examples would be Thymeleaf or FreeMarker. There are some framework, which offer a lot more than templating like Vaadin or Wicket. Some are just specifications like Jakarta Faces with some of their implementations MyFaces or Mojarra.

Keycloak uses FreeMaker to store and render templates. Read more about how Keycloak manages its themes in the official documentation.

For some component types, there is also the possibility to use a Freemarker template instead for more complex UI components. In this case, it will look like this:

From sing-up page to admin portal, you can customize pretty much any part of the UI using custom themes. Themes are developed using Freemarker Templates and it's all documented here.

It now passes the Mustache spec. Arguably better than mustache.java as it adheres to whitespace rules. (BTW I used mustache templating to generate the spec test classes and preferred JMustache over mustache.java exactly because JMustache follows the whitespace rules.)