CodeCrafters CodeCrafters

Build your own Claude Code

Learn about LLM APIs, tool calling, agent loops and more

Start Building
C
C
C#
C#
C++
C++
Go
Go
Java
Java
JavaScript
JavaScript
Python
Python
Rust
Rust
TypeScript
TypeScript
Zig
Zig

This challenge is free to try when it's in beta. We keep challenges in beta for a few weeks to gather feedback.

Claude Code is a terminal-based AI coding assistant that uses Large Language Models (LLMs) to understand code and complete programming tasks. In this challenge, you'll build your own Claude Code that is capable of editing files, running commands, and iterating until the task is done.

Along the way, you'll learn about LLM APIs, tool calling, agent loops, and how to integrate multiple tools into an AI assistant.

What exactly will I build?
What exactly will I learn?
Why should I build such a project?
What are the pre-requisites for this challenge?

Stages

Communicate with the LLM
Login via GitHub to view this stage
Advertise the read tool
Login via GitHub to view this stage
Execute the read tool
Login via GitHub to view this stage
Implement the agent loop
Login via GitHub to view this stage
Implement the write tool
Login via GitHub to view this stage
Implement the bash tool
Login via GitHub to view this stage
“ There are few sites I like as much that have a step by step guide. The real-time feedback is so good, it's creepy! avatar Ananthalakshmi Sankar Automation Engineer at Apple “ I think the instant feedback right there in the git push is really cool. Didn't even know that was possible! avatar Patrick Burris Senior Software Developer, CenturyLink