With Google Apps SSO integration,

• Agents can log in to HappyFox using their Google Apps credentials without the need for a dedicated HappyFox username and password.
• Contacts can log in to HappyFox using their Google Apps credentials.
• For new agents, first login attempt will create new agent accounts that can subsequently be approved by a HappyFox admin.

If you're looking for Google Plus SSO, refer to this article. You would need an existing Google Suite subscription to make this integration work.

Available in all pricing plans. 

How to enable Google Apps SSO?

• Go to Apps >> Single Sign-on >> Google Apps.
• Click Install.
• Under Agent domains, provide the Google Apps domains you would like to enable SSO for.
• Under Contact domains, provide the Google Apps domain you would like to enable SSO for. You can associate each domain to one or more multi-brands.
• Click Save. This enables the integration.

Google Apps SSO workflow for an Agent:

Google Apps SSO workflow for a Contact: