I haven't looked at the code in ages, but it's probably the only scaled consumer web application written in Scala and moreover running on Scala 3 that you can see the end-to-end source for. You have all the Twitter open source Scala projects, of course, but that's just infrastructure for running a web application, rather than an actual production quality app -- and my sense is that in 2024 there aren't many product teams outside of Twitter using their application tooling (as opposed to some of their data infrastructure, certainly the area where Scala sees the most use today with Spark etc).

TLDR if you want to see production-quality Scala code that this very second is serving 40k chess games -- and mostly bullet/blitz where ms latency is of course crucial -- definitely take a look.

Not as much hype for the language at the moment over Rust or Kotlin, say, but it remains my language of choice for web backends by far.