SlideShare

http://en.wikipedia.org/wiki/SlideShare 
https://www.youtube.com/results?search_query=SlideShare

The two products always had kind of similar missions,” Adler said. “The difference was, [SlideShare] focused on more on PowerPoint presentations and business users, while we focused more on PDFs and Word docs and long-form written content, more on the general consumer.

https://techcrunch.com/2020/08/11/scribd-acquires-slideshare/

https://www.scribd.com/