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 November 2025!
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Build your own Redis
Learn about TCP servers, the Redis protocol and more
FREE THIS MONTH
This challenge is free until 1 November 2025!
Start
Build your own grep
Learn about regex syntax: character classes, quantifiers and more
FREE THIS MONTH
This challenge is free until 1 November 2025!
Start
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.
321 stages
Start
Go
Popular
This track is a favourite among our learners.
321 stages
Start
Python
Popular
This track is a favourite among our learners.
321 stages
Start
C
273 stages
Start
C#
321 stages
Start
C++
321 stages
Start
Clojure
196 stages
Start
Crystal
89 stages
Start
Dart
14 stages
Start
Elixir
258 stages
Start
Gleam
297 stages
Start
Haskell
152 stages
Start
Java
321 stages
Start
JavaScript
321 stages
Start
Kotlin
321 stages
Start
OCaml
173 stages
Start
Odin
196 stages
Start
PHP
239 stages
Start
Ruby
189 stages
Start
Scala
89 stages
Start
TypeScript
321 stages
Start
Zig
321 stages
Start