Using Google API's for one's own account without OAuth

Question

Specifically, I'd like to use the Gmail API to access my own mail only. Is there a way to do this without OAuth and just an API key and/or client id and secret?

Using an API key like:

require('googleapis').gmail('v1').users.messages.list({ auth: '<KEY>', userId: '<EMAIL>') });

yields the following error:

{ errors: 
   [ { domain: 'global',
       reason: 'required',
       message: 'Login Required',
       locationType: 'header',
       location: 'Authorization' } ],
  code: 401,
  message: 'Login Required' }

I suppose that message means they want a valid OAuth "Authorization" header. I would do that but I suppose that's not possible without presenting a webpage.

Answer 1

The strict answer to "Is there a way to do this without OAuth and just an API key and/or client id and secret?" is no.

However, you can achieve what you are looking for using OAuth. You simply need to store a Refresh Token, which you can then use any time to request an Auth Token to access your gmail.

In order to get the refresh token, you can either write a simple web app to do a one time auth, or follow the steps here How do I authorise an app (web or installed) without user intervention? (canonical ?) which allows you to do the whole auth flow using the Oauth Playground.