I have created a new module for Drupal 7, which harneses the power of Slim Framework to create an API for Drupal content types and users.

Slim is a PHP micro framework that helps you quickly write simple yet powerful web applications and APIs.
At its core, Slim is a dispatcher that receives an HTTP request, invokes an appropriate callback routine, and returns an HTTP response.
That’s it.

The module creates 8 endpoints which return data in JSON format and are accessable via a GET or POST request to create, read, update or delete nodes.

https://www.drupal.org/project/simple_slim_api

https://stackoverflow.com/questions/50504074/how-can-i-use-slim-micro-framework-inside-drupal/54674133#54674133

I have plans to port this code to Drupal 8, but my current development path for this module before that is to add connectivity for the excellent Search API module https://www.drupal.org/project/search_api

It felt good to give back to the Drupal project.

Peace to all.