This domain primary activity is Content Delivery Network (CDN). If you are not familiar with CDN find https://en.wikipedia.org/wiki/Content_delivery_network
Fastly is not open source. But they extensively support lots of open source projects such as Drupal, Debian, Linux Kernel Organization, TOR. Read more at https://www.fastly.com/open-source
This domain name is owned by the for profit corporation Fastly, Inc.
So there is a potential risk that they or will collect your private information to try to monetize it.
Source at https://www.fastly.com/investors and https://www.fastly.com/contact-us
Fastly are located at 475 Brannan St. #300
San Francisco, CA 94107.
Read more about Fastly at https://www.fastly.com