When I want to know things like this (and I usually do) I take a look at their Jobs listings, this usually reveals the technologies used, in this case I found:

When I want to know things like this (and I usually do) I take a look at their Jobs listings, this usually reveals the technologies used, in this case I found: Disqus is the largest Django application and one of the largest pure Python implementations on the web. We love JavaScript and write highly optimized code with performance and compatibility in mind.