When viewing a site's referring pages, you have the option to filter them based on their "Platform". This filter can be found on Backlinks, Referring Domains, Best by Links, and any other Site Explorer report that has data on referring pages.
To find this filter on any supported report, look for "+ More filters", and click on "Platform" under the Referring page section:
From the image above, the platforms you can filter by in Ahrefs are:
Blogs - This is a platform where bloggers/writers publish their content for informative and/or educational purposes.
Ecommerce - An ecommerce platform is an online storefront that allows products and/or services to be sold to customers/users.
Message boards - Also known as Discussion Boards or Forums; a message board is a platform where persons of similar interest in a topic or subject share their views and ideas.
Wikis - A website or database developed collaboratively by a community of users, allowing any user to add and edit content.
CMS (Content Management System) - This platform is used to create and administer digital content. An example of a CMS is the Wordpress platform.
Here's an example of filtering for "Platform" of "Message boards" in the Backlinks report for ahrefs.com. In the image below, you will notice that the Referring pages are tagged with the platform type, consisting of "Message boards":