Claude Code (CLI)

by Anthropic - terminal-native agentic coding assistant

Claude Code is Anthropic's terminal-native AI coding tool. Unlike editor plugins, it runs directly in your shell - giving it full access to your filesystem, git history, terminal output, and the ability to run commands. It is the most powerful option for agentic tasks: give it a goal and it autonomously reads files, writes code, runs tests, and iterates.

Made by

Anthropic

Interface

Terminal (CLI)

Requires

Claude Pro or API

Platform

Mac, Linux, WSL

Model

Claude Opus 4.8 / Sonnet 4.6

Install via

npm (Node.js)

⚡ Install & Setup

Install Node.js

Claude Code requires Node.js 18+. Download from nodejs.org or run: brew install node (Mac).

Install Claude Code

Run in terminal: npm install -g @anthropic-ai/claude-code

Authenticate

Run: claude - on first launch it opens your browser to sign in with your Anthropic account. Requires Claude Pro ($20/month) or an API key (pay-per-use, very affordable for coding tasks).

Verify installation

Run: claude --version - you should see the version number. Then cd into any project and run: claude

# Install and launch

npm install -g @anthropic-ai/claude-code
cd my-project
claude

🚀 Sample Usage

Interactive Mode - Ask & Iterate

$ claude
> Explain the auth flow in this project
[Claude reads src/auth/, middleware, and routes, then explains]

> Add JWT refresh token rotation. Write tests too.
[Claude creates files, runs npm test, fixes failures, done]

One-Shot Commands (non-interactive)

# Ask a question and get output:
claude "What does the processPayment function do?"

# Pipe a diff for review:
git diff --staged | claude "Review this diff before I commit"

# Run a file through Claude:
claude "Add error handling to all async functions" src/api/users.ts

CLAUDE.md - Persistent Project Context

Create a CLAUDE.md file in your project root. Claude Code reads it automatically every session:

# CLAUDE.md
## Stack Node.js + Express + PostgreSQL
## Conventions
- Use AppError for all errors (src/lib/errors.ts)
- No console.log - use logger from src/lib/logger.ts
## Tests vitest, run with npm test

💡 Pro Tips

Always start agentic tasks in a clean git branch - Claude will modify multiple files
The CLAUDE.md file is your most powerful tool - detailed context = better output
Use Ctrl+C to interrupt Claude mid-task and redirect it
Press y to accept file changes, n to reject, or type a correction
API key mode (no Pro required): set ANTHROPIC_API_KEY in your environment and billing kicks in at ~$0.003/1K tokens

⚖️ Which Coding Tool Should I Pick?

The current tool is highlighted. There is no single winner - pick by how you like to work.

Tool	Type	Pricing	Best for	Models / AI
GitHub Copilot	IDE extension	Free tier; Pro ~$10/mo	AI in your existing editor	GPT-5.5, Claude Sonnet 4.6, Gemini 3.5
Cursor	AI IDE (VS Code fork)	Hobby free; Pro $20/mo	All-round AI editor + agent	GPT-5.5, Claude Opus 4.8 / Sonnet 4.6
Windsurf	AI IDE (VS Code fork)	Free tier; paid plans	Agentic flows (Cascade)	Frontier models + own
Google Antigravity	Agent-first IDE	Free public preview	Autonomous build + browser test	Gemini 3.5
Claude Code (CLI)(this page)	Terminal agent	Claude sub or API	Agentic coding in the terminal	Claude Opus 4.8 / Sonnet 4.6 / Haiku 4.5
VS Code + AI ext	Editor + extensions	Free options exist	Keep VS Code, add AI	Depends on extension

Pricing and model support change often. Verified June 2026 - confirm on each tool's official site.

🛠️ Troubleshooting & Common Pitfalls

⚠ command not found: claude

Re-run the global install and make sure your npm global bin directory is on your PATH. Restart the terminal afterward.

⚠ Authentication errors

⚠ Too many permission prompts

Configure allowed tools / commands in settings, or run with the right permission mode - but review what you allow.

⚠ Token costs climbing

Scope each task, use /clear to reset context between tasks, and prefer a cheaper model (Haiku) for simple jobs.

📚 Related Course Lessons

Go deeper on the skills this tool is for:

L46 - Agentic Coding →L47 - Custom AI Extensions →L56 - From Prompter to Loop Designer →L59 - Skills →

🔗 Official Resources

Product page ↗What it is + how to install Documentation ↗Commands, CLAUDE.md, MCP, agents npm package ↗npm i -g @anthropic-ai/claude-code GitHub repo ↗Issues + source Pricing ↗Subscription + API rates

Links open the official sites. Pricing and features change often - always confirm there. (Verified June 2026.)

→ Compare: GitHub Copilot → Compare: Windsurf