Our entire backend is written in Haskell. Our backend comprises several pieces:Scarf Gateway, which is a redirect and proxy layer that can sit in front of any package/artifact registry or service you use, and provides advanced analytics about your software’s usage traffic. Since Scarf Gateway sits in front of package registries, it’s really important for it to be highly available, fast, and correct.Events from Scarf Gateway are then streamed via Kafka and processed reactively, in addition to a growing system of scheduled batch processing jobs.On the more traditional web development side, our Haskell backend powers our web app with a straightforward JSON API. OSS maintainers use our web app to manage their packages on Scarf as well as visualize the analytics that our system has processed for them.