I have been working on this recently, using nginx as the reverse proxy. Nginx makes it pretty trivial to limit requests based on various factors, like request rate, number of connections, etc. A post like https://lincolnloop.com/blog/rate-limiting-nginx/ has snippets that show how it works.
But the simplification is that you do not need to write any application code. I can very easily have certain routes or domains limited differently by updating the nginx config. Especially in a microservices world I am trying to avoid having to update N services to get all of them to be rate limited.