CodeCrafters CodeCrafters

Challenges

New here? Start here to learn how challenges work.

Build your own Shell
Build your own Shell
Learn about parsing shell commands, executing programs and more
59 stages
Build your own Redis
Build your own Redis
Learn about TCP servers, the Redis protocol and more
97 stages
Build your own grep
Build your own grep
Learn about regex syntax: character classes, quantifiers and more
33 stages
Build your own Interpreter
Build your own Interpreter
Learn about tokenization, ASTs, tree-walk interpreters and more.
84 stages
Build your own BitTorrent
Build your own BitTorrent
Learn about .torrent files, the BitTorrent Peer Protocol and more
19 stages
Build your own Kafka
Build your own Kafka
Learn about TCP servers, the Kafka wire protocol and more.
FREE DURING BETA
This challenge is free to try when it's in beta. We keep challenges in beta for a few weeks to gather feedback.
Start
Build your own Git
Build your own Git
Learn about git objects, plumbing commands and more
7 stages
Build your own SQLite
Build your own SQLite
Learn about SQL syntax, SQLite's file format, B-trees and more
9 stages
Build your own DNS server
Build your own DNS server
Learn about the DNS protocol, DNS record types and more.
8 stages
Build your own HTTP server
Build your own HTTP server
Learn about TCP servers, the HTTP protocol and more
14 stages
Build your own Claude Code
Build your own Claude Code
Learn about LLM APIs, tool calling, agent loops and more
FREE DURING BETA
This challenge is free to try when it's in beta. We keep challenges in beta for a few weeks to gather feedback.
Start

Language Tracks

Rust
Rust
Popular
This track is a favourite among our learners.
361 stages
Start
Go
Go
Popular
This track is a favourite among our learners.
361 stages
Start
Python
Python
Popular
This track is a favourite among our learners.
361 stages
Start
C
C
336 stages
Start
C#
C#
361 stages
Start
C++
C++
361 stages
Start
Clojure
Clojure
204 stages
Start
Crystal
Crystal
97 stages
Start
Dart
Dart
73 stages
Start
Elixir
Elixir
282 stages
Start
Gleam
Gleam
321 stages
Start
Haskell
Haskell
229 stages
Start
Java
Java
361 stages
Start
JavaScript
JavaScript
361 stages
Start
Kotlin
Kotlin
347 stages
Start
OCaml
OCaml
240 stages
Start
Odin
Odin
273 stages
Start
PHP
PHP
273 stages
Start
Ruby
Ruby
213 stages
Start
Scala
Scala
156 stages
Start
TypeScript
TypeScript
361 stages
Start
Zig
Zig
353 stages
Start