This service accepts a string as a parameter and will check whether it is either a human readable date or a Unix timestamp. If it is, it will return both the Unix timestamp and the natural language form of that date as a JSON object. If it is neither, it returns 'null' for those properties.
You can access the API through a browser or by creating an ajax get request.
https://timestamp-micro-srvc.herokuapp.com/December 15, 2015
"natural": "December 15, 2015"