Read code with Claude
Understand any codebase in minutes
⏱ Est. ~8 min
01 · Read
One of Claude Code's most powerful uses is understanding code you didn't write. This is a skill every engineer needs constantly — when joining a new team, when exploring open source projects, when coming back to your own code months later.
Before Claude Code, understanding a new codebase took hours of reading files, tracing function calls, and piecing together how everything connects. Now you just ask.
Let's practice reading code with Claude. Start Claude Code in any project you have — ideally the one from Level 7, or any project with a few files.
💡 Picture thisImagine being dropped into a new city with no map. You could spend hours wandering and figuring out where everything is. Or you could ask a local who knows every street. Claude Code is that local — except it knows every line of code.
02 · Prompt template
Start with the big picture. Ask Claude for an overview of the whole project — what it does and how it's organized.
Give me an overview of this project — what does it do, and how is it structured?
03 · Prompt template
Now zoom in. Pick the main file of the project and ask Claude to walk you through it line by line.
Walk me through the main file line by line
04 · Prompt template
If your project has a package.json, ask Claude to explain your dependencies. If it doesn't, skip this step.
What packages does this project use? What is each one for?
05 · Quiz
You ask Claude Code to explain a function in your project. What's its biggest advantage over pasting the same code into Claude.ai?
- It can run the code automatically to confirm the explanation
- It can read every other file the function depends on, with context
- It responds faster than the web app
- It uses a stronger model than Claude.ai
06 · Fill in the blank
To ask Claude to explain the file you're currently looking at, a common English phrasing is "Explain what _____ does" — the blank is usually filled with "this file." What goes in the blank?
07 · Read
This is what real engineers do every day. You join a company, you're dropped into a codebase with thousands of files you've never seen. Your first job is to understand it.
Before AI tools, this could take weeks. Engineers would read documentation (if it existed), trace code by hand, and ask teammates. Claude Code massively speeds up this process.
Even experienced engineers use this pattern constantly. Understanding code is just as important as writing it.
08 · Quiz
A coworker sends you a link to a GitHub repo you've never seen. What's the fastest way to understand what the project does using Claude Code?
- Clone the repo, cd into it, run claude, and ask for an overview of the project
- Read every file manually, starting with the README
- Copy each file one by one into Claude.ai
- Google the project name and read blog posts
09 · Fill in the blank
Claude Code reads your real _____ to give accurate answers, instead of guessing.
Other lessons in this chapter
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※ This is an independent Traditional Chinese teaching project — not an official Anthropic product. Claude™ is a trademark of Anthropic, PBC.