CodeCrafters
Challenges
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Build your own HTTP server
Learn about TCP servers, the HTTP protocol and more
FREE THIS MONTH
This challenge is free until 1 May 2025!
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Build your own Shell
Learn about parsing shell commands, executing programs and more
28 stages
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Build your own grep
Learn about regex syntax: character classes, quantifiers and more
15 stages
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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.
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Build your own Redis
Learn about TCP servers, the Redis protocol and more
55 stages
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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
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Build your own SQLite
Learn about SQL syntax, SQLite's file format, B-trees and more
9 stages
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Build your own DNS server
Learn about the DNS protocol, DNS record types and more.
8 stages
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Language Tracks
Rust
Popular
This track is a favourite among our learners.
254 stages
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Go
Popular
This track is a favourite among our learners.
254 stages
Start
Python
Popular
This track is a favourite among our learners.
254 stages
Start
C
221 stages
Start
C#
254 stages
Start
C++
254 stages
Start
Clojure
55 stages
Start
Crystal
55 stages
Start
Dart
11 stages
Start
Elixir
85 stages
Start
Gleam
220 stages
Start
Haskell
107 stages
Start
Java
254 stages
Start
JavaScript
254 stages
Start
Kotlin
236 stages
Start
OCaml
139 stages
Start
PHP
182 stages
Start
Ruby
137 stages
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Scala
55 stages
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TypeScript
152 stages
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Zig
206 stages
Start