It will allow your customers to login with their facebook account or google account in your opencart site.See the demo images.
It supports multi-store.
Demo : https://demo.soft-php.com/joocart-extensions/index.php/account/login

Installation

1. Go to o your store admin panel. Navigate to Extensions -> Extension installer.
2. Click on the upload button. A dialog box should open.
3. Locate the installation file of this extension(facebook_google_login.ocmod.zip) and select it.
4. Now this module named "Login with Facebook and Google" should be visible in Extensions -> Modules.
    After locating it in the Module list just click the install button (“ + ” sign)
    Then edit this installed module and enable it.
5. Refresh the modifications from Extensions->Modifications
6 Go to System->Settings->Store Name[Edit]->Facebook & Google Tab
7. Configure it by putting facebook and google application credentials and save
8. Now you can see login with facebook and google features in frontend.
9. Done