Open Graph Previewer от Ruben

Click on the add-on icon in the toolbar and then on the Turn on button to enable the add-on.

You will find the extension in the devtools under Open Graph Previewer. Now whenever you visit a site, the extension will get all open graph tags met the DOM used on the page and show them alongside generating cards for facebook and twitter. This way you can easily see how the site will look like when shared on social media.