I just wanted to leave this here in case if anyone works with CakePHP 3 framework. It's a plugin written by me, that allows you to "bake" (that means, generate code) a controller only for API use.
This stands for:
1) Left the standard index, view, add, edit and delete
2) Removed every redirect
3) Added the _serialize variable setting
This is the repository:
Also, I'm open to contributions. One thing I want to investigate is OpenGl. I think it would be useful to have an endpoint that can work with that specification and retrieve results based on filters.