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Jenny Met
Jenny Met

Posted on • Originally published at crazyrouter.com

Claude Code Complete Tutorial: From Installation to Production (2026)

#claudecode #ai #programming #tutorial

What is Claude Code?

Claude Code is Anthropic's official AI coding assistant that runs directly in your terminal. Unlike Cursor or GitHub Copilot, it understands your entire codebase and can edit multiple files simultaneously.

Key capabilities:

  • 🔍 Understands full project context (not just the open file)
  • ✏️ Edits multiple files in a single command
  • 🖥️ Executes shell commands (tests, builds, deploys)
  • 🗣️ Natural language interaction — describe what you want, AI delivers

Best for: Backend development, scripting, automation, CI/CD integration, code review.

Installation

Requirements

  • Node.js 18.0+
  • macOS, Linux, or Windows 10+
  • Terminal with ANSI color support

Install 

# npm (all platforms)
npm install -g @anthropic-ai/claude-code

# Verify
claude-code --version
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Configuration

Option 1: Official Anthropic API 

export ANTHROPIC_API_KEY="sk-ant-api03-xxxxx"
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Pricing: Claude Opus 4.6 — $15/M input, $75/M output tokens.

Option 2: API Gateway (Recommended — 45% Cheaper)

Why use an API gateway?

  • 45% cheaper than official pricing
  • 600+ models with one key (Claude + GPT + Gemini + DeepSeek)
  • Better international latency
  • No credit card required (Alipay/WeChat supported) 
export ANTHROPIC_API_KEY="sk-xxxxxx"  # Your gateway key
export ANTHROPIC_BASE_URL="https://crazyrouter.com/v1"
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Method Input Price Output Price Savings
Official API $15/M $75/M —
API Gateway $8.25/M $41.25/M 45%

Get your API key →

Core Usage 

# Start in your project
cd /path/to/project
claude-code
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Essential Commands

Command Description
/add <path> Add files/dirs to context
/clear Clear conversation history
/model <name> Switch model
/cost Show session cost
/exit Quit

Real-World Examples

Create a REST API 

> Create a Flask REST API with:
> 1. GET /users - list all users
> 2. POST /users - create user with validation
> 3. SQLite database
> 4. Error handling and logging
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Claude Code creates app.py, models.py, requirements.txt, init_db.py — all tested and runnable.

Refactor Entire Codebase 

> Convert all sync functions in src/ to async/await
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Scans all Python files → identifies sync functions → converts to async → updates all call sites → adds asyncio imports.

Security Audit 

> Review src/auth.py for security vulnerabilities
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Output:

🔴 Security Issues:
  - Line 45: Passwords stored unencrypted
  - Line 78: SQL injection risk (string concatenation)

🟡 Performance:
  - Line 120: N+1 query in loop
  - Line 156: Missing database index

✅ Recommendations:
  1. Use bcrypt for password hashing
  2. Switch to parameterized queries
  3. Add composite index on (user_id, created_at)
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Generate Tests 

> Generate unit tests for all functions in src/api.py
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Creates tests/test_api.py with happy path, edge cases, error handling, and mocked dependencies.

Advanced: CI/CD Integration 

# .github/workflows/ai-review.yml
name: AI Code Review
on: [pull_request]
jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
        with:
          node-version: '18'
      - run: npm install -g @anthropic-ai/claude-code
      - name: AI Review
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
          ANTHROPIC_BASE_URL: "https://crazyrouter.com/v1"
        run: |
          claude-code --read-only --non-interactive \
            "Review this PR for bugs, security issues, and style" \
            > review.txt
          cat review.txt >> $GITHUB_STEP_SUMMARY
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Claude Code vs Cursor vs Copilot

Feature Claude Code Cursor Copilot
Interface Terminal GUI (VS Code) IDE Plugin
Full codebase context ✅ ⚠️ Limited ❌
Multi-file editing ✅ ✅ ❌
Custom API endpoint ✅ ❌ ❌
CI/CD integration ✅ ❌ ❌
Price Pay-per-token $20/mo $10/mo
Model flexibility ✅ Any model Claude only GPT only

Choose Claude Code if: you do backend work, need CI/CD integration, want model flexibility, or prefer terminal workflows.

Choose Cursor if: you prefer visual editing and work primarily on frontend.

Cost Optimization

  1. Use Sonnet 4.5 for simple tasks — 5x cheaper than Opus 4.6
  2. Clear context with /clear when switching topics
  3. Use an API gateway — save 45% on every API call
  4. Monitor spending with /cost command
  5. Batch similar tasks instead of making many small requests

FAQ

Q: Does Claude Code upload my entire codebase?
Only files you add to context via /add or that Claude requests to read. Use --read-only for extra safety.

Q: Which languages are supported?
All major languages: Python, JavaScript/TypeScript, Go, Rust, Ruby, PHP, Swift, Kotlin, C/C++, SQL, and more.

Q: Can I use non-Claude models?
Yes! With an API gateway:

/model gpt-4o
/model gemini-2.5-pro
/model deepseek-v3
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Q: How do I handle rate limits?
Use an API gateway with automatic fallback — if one provider is rate-limited, it routes to another model automatically.

Q: Is my code secure?
Code is sent to the API provider (Anthropic or your gateway). For sensitive codebases, consider self-hosting or using --read-only mode.

Get Started

  1. Install: npm install -g @anthropic-ai/claude-code
  2. Get an API key: crazyrouter.com (45% cheaper, 600+ models)
  3. Configure: export ANTHROPIC_BASE_URL="https://crazyrouter.com/v1"
  4. Start coding: claude-code

Try Crazyrouter — one API key for 600+ AI models, 45% cheaper than going direct. crazyrouter.com

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