In the past, disqus was the solution to go for when you needed a functionality for your static website that would enable people to post comments and ask questions under your posts.
With it's free tier, you would get a package with basic features. It comes with a price though of it being relatively heavy solution.
It's ads supported and increases page weight by factor of 10! Not to mention it lets other applications like Facebook to track your visitors.
So recently when I was in middle of integration of disqus plugin to this blog, I decided to revisit my product of choice and explore other options in nowadays product driven market.