Basilisk is a static website generator that builds HTML websites from a set of static files in multiple formats, such as HTML, markdown or plain text. It is designed in a modular way which makes it easily extensible. I use Basilisk to generate several of my websites, including this one. I guess the joke that an unwritten rule states that it is mandatory for every programmer to write a static website generator is true.
Nearly all core functionality of the program is provided in the form of swappable and replaceable modules which means that it can easily use different template systems, support many different input file formats or extend the existing functionality by implementing additional features such as blog systems or other mechanisms used for serving specific types of content.
The program comes with multiple built-in modules implementing various functionalities like using Jinja2 templates, converting UNIX manual files, resizing images, minifying HTML, prettifying urls and so on.