Looking for logging into the Guzzle 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 Guzzle site. After that you can login as usual with your login credentials.
https://stackoverflow.com/questions/25089960/how-to-get-past-login-screen-on-guzzle-call
http://www.pixelite.co.nz/article/guzzle-http-post-authentication-and-form-submission-symfony-20/
http://docs.guzzlephp.org/
https://www.guzzle.co.za/accounts/login/
https://github.com/guzzle/guzzle/issues/1817
https://github.com/guzzle/guzzle/issues/1400
https://hackernoon.com/creating-rest-api-in-php-using-guzzle-d6a890499b02
https://laracasts.com/discuss/channels/laravel/guzzle-http-with-basic-auth-example
https://www.youtube.com/watch?v=GfZLYsgtm-4
https://eureka.ykyuen.info/2013/09/04/drupal-8-login-in-guzzle-web-service-client/
https://drupal.stackexchange.com/questions/221946/how-do-you-perform-a-guzzle-post-request-with-basic-auth-for-the-current-user
https://www.youtube.com/watch?v=kKppYrHbO3Y
https://www.youtube.com/watch?v=4J7p0CZ0aQ4