CodeCrafters
Challenges
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Build your own HTTP server
Learn about TCP servers, the HTTP protocol and more
14 stages
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Build your own Shell
Learn about parsing shell commands, executing programs and more
43 stages
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Build your own grep
Learn about regex syntax: character classes, quantifiers and more
FREE THIS MONTH
This challenge is free until 1 September 2025!
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Build your own Interpreter
Learn about tokenization, ASTs, tree-walk interpreters and more.
84 stages
Start
Build your own Redis
Learn about TCP servers, the Redis protocol and more
FREE THIS MONTH
This challenge is free until 1 September 2025!
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Build your own BitTorrent
Learn about .torrent files, the BitTorrent Peer Protocol and more
19 stages
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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.
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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.
294 stages
Start
Go
Popular
This track is a favourite among our learners.
294 stages
Start
Python
Popular
This track is a favourite among our learners.
294 stages
Start
C
257 stages
Start
C#
294 stages
Start
C++
294 stages
Start
Clojure
96 stages
Start
Crystal
73 stages
Start
Dart
14 stages
Start
Elixir
242 stages
Start
Gleam
270 stages
Start
Haskell
132 stages
Start
Java
294 stages
Start
JavaScript
294 stages
Start
Kotlin
276 stages
Start
OCaml
157 stages
Start
Odin
176 stages
Start
PHP
219 stages
Start
Ruby
173 stages
Start
Scala
73 stages
Start
TypeScript
294 stages
Start
Zig
294 stages
Start