Scalaing Challenge Leaderboards for Millions of Users

Strava challenges offer a fun way for athletes to compete against themselves and others! Back in 2020, our legacy challenge leaderboard system was running into bottlenecks and scalability problems on a regular basis, and we often found ourselves putting out fires to keep the system stable. In late 2020 and early 2021, I worked on a project to replace the old leaderboard system with a new one that could handle a much larger number of athletes competing in challenges. This blog post is about that project. I drafted most of this post when the project wrapped up in 2021, but didn’t get it published before I went on paternity leave – and then I forgot about it. I think the project was interesting and worth sharing, so I’m glad I finally remembered my draft (three years later 🫣) and found some time to put in the finishing touches and get it published! Enjoy!