Marten, the Crystal web framework
Wow, if Django and Rails had a baby it would be Marten, the web framework written in Crystal, https://martenframework.com/.
It seems fairly feature-complete, even with only a 0.1.x version number! https://martenframework.com/docs/.
The documentation looks really solid. Clearly they just love to program and give to open-source! https://github.com/martenframework.