How to add Google Authenticator to my website? : <p>I have a web app that is Angular2 on the front-end and NodeJS on the back-end.  I want to allow clients to use Google Authenticator to make their accounts more secure.</p>

<p>How can I implement/use Google Authenticator in my website?  I cannot find an API to use or and tutorials to follow or any libraries to use.  Where can I find some resources to do this?</p>
