7 – Upload a JSON from a third-party application

I have a client hosted in Acquia and they are asking us to implement the functionality to allow another third-party application from a company to upload a JSON file to a loading directory within their Drupal 7 website or, alternatively, send POST data json to your website. save it as a json file in the loading directory of Drupal 7.

Is this possible with Drupal 7? Services? Post request with ftp credentials?