Product notes
Product updates, new challenges, and improvements, newest first.
Language leaderboards begin rolling out
Language rankings were publicly announced after an earlier limited rollout, showing nearby ranks and progress.
Autofix output is removed from terminal submissions
CLI and Git submissions no longer print Autofix output.
Build your own Claude Code
Released in beta, this challenge covers LLM APIs, tool calling, and agent loops that edit files and run commands.
Notifications when voted-for content ships
Release emails first covered extensions learners voted for, then expanded to challenge releases.
Formatted code examples in every language
Automatic formatting expanded to every supported language, making community solutions easier to read.
Build a DNS Server in Elixir
The DNS Server challenge now supports Elixir.
Build an HTTP Server in OCaml
The HTTP Server challenge now supports OCaml.
Autofix reaches every base Shell stage
The experimental Autofix feature expanded from the first four Shell stages to all base stages.
Build a Shell in Scala
The Shell challenge now supports Scala.
Extend a membership before it expires
Pay for more membership time before your current membership ends.
See your next leaderboard milestone
The challenge sidebar shows your language leaderboard and the stage progress needed to reach a higher rank.
Build Kafka in Elixir
The Kafka challenge now supports Elixir.
Reading is good.
Doing is better.
Build your own Claude Code, Shell, or SQLite. Understand what’s underneath.