I just released the ratelimit gem. It was inspired by this article.

This is not intended to replace Rack::Throttle or any other inbound rate limiter but rather to help rate limit outbound traffic (SMS messages, emails etc). See the above article for specifics but it uses a bucketing method such that the rate limit is tracked as a rolling window rather than in large chunks like hours or days at a time. It uses Redis as a backend store meaning you can limit across multiple processes and/or servers.

Thanks!