How does the Facebook Crawler work?
You can use the Sharing Debugger to see the information that is used when your website content is shared on Facebook, Messenger and other places. The Batch Invalidator will let you refresh this information for multiple URLs at the same time. Open Graph markup lets you take control over how your website content appears to others. Learn More
The Access Token Debugger lets you see the information associated with a particular access token from someone who's logged into your app with Facebook.