Enable Google API for "googleapis.com/auth/userinfo"

You will need to at least add the scope https://www.googleapis.com/auth/userinfo.profile as per mentioned.

Then you can use the oauth2 apis just like how would you use sheets, calendar etc.

In nodejs, it'd be something like this:

    const { google } = require('googleapis')
    const auth = new google.auth.OAuth2(
      keys.web.client_id,
      keys.web.client_secret,
      keys.web.redirect_uris[0]
    )
    // get the tokens from google
    auth.credentials = tokens
    const oauth2 = google.oauth2({ version: 'v2', auth })
    const userinfo = await oauth2.userinfo.get()
    console.log(userinfo)

The api is documented here: https://googleapis.dev/nodejs/googleapis/latest/oauth2/interfaces/Schema$Userinfo.html#info. There are also some examples in the source code there.

If you need just user's email-address for auth etc., you have to enable Google's Plus API, not the G**-*****d People API which is mentioned everywhere in the Google Cloud API docs.

Also, you need to mention the scope https://www.googleapis.com/auth/userinfo.email, not the https://www.googleapis.com/auth/userinfo.profile one.

p.s. It's an old question, yet unanswered. Possibly, you've already solved it. I'm posting it for people from the future, or just for my future self.

You can retrieve data from these endpoints if you have an access token from the user. First, you have to get an access token by letting the user login using google login API. Then retrieve the data from the following link. https://www.googleapis.com/oauth2/v1/userinfo?access_token=PUT_YOUR_USER'S_ACCESS_TOKEN_HERE