My JSON:API Server framework was born from a need for a slightly opinionated server to serve an API that subscribed strongly to the JSON:API spec. I choose to write my own after trying a number of other frameworks, but found none that gave me exactly what I was looking for. They were either too opinionated or not opinionated enough.
I began this work for a freelance project required a major rebuild of their API in order to more smoothly handle related resources. JSON:API provides a very clear way to return related resources for a RESTful API.
Work has stalled on this particular project. The client ended up going a different direction. I had originally planned to return to this framework, but have not found the time or interest. In the intervening years a number of new approaches have popped up making this particular need a little obsolete.