CodeCrafters
Challenges
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Build your own Shell
Learn about parsing shell commands, executing programs and more
FREE THIS MONTH
This challenge is free until 1 December 2025!
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Build your own Redis
Learn about TCP servers, the Redis protocol and more
97 stages
Build your own grep
Learn about regex syntax: character classes, quantifiers and more
25 stages
Build your own Interpreter
Learn about tokenization, ASTs, tree-walk interpreters and more.
84 stages
Build your own BitTorrent
Learn about .torrent files, the BitTorrent Peer Protocol and more
19 stages
Build your own Kafka
Learn about TCP servers, the Kafka wire protocol and more.
25 stages
Build your own Git
Learn about git objects, plumbing commands and more
7 stages
Build your own SQLite
Learn about SQL syntax, SQLite's file format, B-trees and more
9 stages
Build your own DNS server
Learn about the DNS protocol, DNS record types and more.
8 stages
Build your own HTTP server
Learn about TCP servers, the HTTP protocol and more
14 stages
Language Tracks
Rust
Popular
This track is a favourite among our learners.
331 stages
Start
Go
Popular
This track is a favourite among our learners.
331 stages
Start
Python
Popular
This track is a favourite among our learners.
331 stages
Start
C
306 stages
Start
C#
331 stages
Start
C++
331 stages
Start
Clojure
204 stages
Start
Crystal
97 stages
Start
Dart
14 stages
Start
Elixir
266 stages
Start
Gleam
307 stages
Start
Haskell
162 stages
Start
Java
331 stages
Start
JavaScript
331 stages
Start
Kotlin
331 stages
Start
OCaml
181 stages
Start
Odin
206 stages
Start
PHP
249 stages
Start
Ruby
197 stages
Start
Scala
97 stages
Start
TypeScript
331 stages
Start
Zig
331 stages
Start