The following is the Prolog help page on the Kattis Problems Archive.

https://open.kattis.com/help/prolog

Kattis uses the free SWI-Prolog compiler to judge solutions implemented in Prolog. It may be useful that Codeforces team considers adopting this approach for including Prolog among the programming languages which can be used in Codeforces Rounds and Educational Contests.