Looking for logging into the Google+ Api site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Google+ Api site. After that you can login as usual with your login credentials.
https://developers.google.com/+/web/signin/
https://developers.google.com/+/web/api/rest/
https://developers.google.com/+/web/api/rest/oauth
https://developers.google.com/+/?hl=ja
http://www.koikikukan.com/archives/2014/02/13-013333.php
https://qiita.com/syarihu/items/1c67816ad926f08d76d8
https://qiita.com/edo_m18/items/20fe8426f7c4dc0517dc
https://support.google.com/a/answer/3187191?hl=ja
https://www.drupal.org/project/hybridauth/issues/3021918
https://community.apigee.com/questions/9223/social-login-with-google-how-to-do.html
https://stackoverflow.com/questions/53717693/with-google-being-shutdown-is-the-oauth-api-gone-too
https://stackoverflow.com/questions/27169966/google-api-sign-in-for-both-android-app-and-server