The Linkback module(background information) for Drupal 8 has been tagged alpha today! here a good intro about it written by HongPong. We've done a lot of work to get there!
Note for alpha1 release:
We are proud to bring you the first alpha release of Linkback, an interesting suite of modules which can help integrate your website with the wider internet. Linkback provides the backend functionality to save both outgoing and incoming pings and webmentions involving remote sites.
This first release focuses on a robust, spam resistant and fault tolerant approach to processing and storing Linkbacks as Drupal entities, which provides a standardized and efficient storage structure that can be easily queried and extended. (Anyone interested in improving the theming is invited to file an issue or share code with us :) More information about the functions in the Linkback suite is in Developer.md and the Readme.md files inside each child module.
linkback_pingback creates the appropriate endpoints on your site to receive pingbacks from other sites (that is, someone on a WordPress site includes a link to your site and attempts to send a pingback; linkback_pingback receives the ping, scans the originating site URL to see if it a really existing anchor there, and if so, then it saves a new Linkback with the pingback handler attached to it.
linkback_webmention provides much the same functionality for your site to send and receive Webmentions. (see other Webmention implementations - this module should interoperate with them). Services such as brid.gy can help connect proprietary content silos like Facebook and Twitter to your webmentions.
Linkback has been cleverly structured to apply the best of Drupal 8 and Symfony architecture while reapplying many of the ideas from its predecessor Vinculum which provided similar services in Drupal 7. It should be feasible to extend Linkback to store other similar types of entities as records of intra-site communication.
Thank you for trying Linkback - it is a product of several years of effort including bringing "indieweb" principles and specifications into Drupal.