CodeCrafters
Challenges
New here?
Start here
to learn how challenges work.
Build your own HTTP server
Learn about TCP servers, the HTTP protocol and more
14 stages
Start
Build your own Shell
Learn about parsing shell commands, executing programs and more
FREE THIS MONTH
This challenge is free until 1 July 2025!
Start
Build your own grep
Learn about regex syntax: character classes, quantifiers and more
15 stages
Start
Build your own Interpreter
Learn about tokenization, ASTs, tree-walk interpreters 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 Redis
Learn about TCP servers, the Redis protocol and more
55 stages
Start
Build your own BitTorrent
Learn about .torrent files, the BitTorrent Peer Protocol and more
19 stages
Start
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
Learn about git objects, plumbing commands and more
7 stages
Start
Build your own SQLite
Learn about SQL syntax, SQLite's file format, B-trees and more
9 stages
Start
Build your own DNS server
Learn about the DNS protocol, DNS record types and more.
8 stages
Start
Language Tracks
Rust
Popular
This track is a favourite among our learners.
272 stages
Start
Go
Popular
This track is a favourite among our learners.
272 stages
Start
Python
Popular
This track is a favourite among our learners.
272 stages
Start
C
239 stages
Start
C#
272 stages
Start
C++
272 stages
Start
Clojure
69 stages
Start
Crystal
55 stages
Start
Dart
14 stages
Start
Elixir
224 stages
Start
Gleam
248 stages
Start
Haskell
110 stages
Start
Java
272 stages
Start
JavaScript
272 stages
Start
Kotlin
254 stages
Start
OCaml
139 stages
Start
Odin
154 stages
Start
PHP
197 stages
Start
Ruby
155 stages
Start
Scala
55 stages
Start
TypeScript
272 stages
Start
Zig
272 stages
Start