Step-by-Step Installation, Authentication, and Usage Guide for Anthropic’s Claude Code in 2025: 🚀 Complete Setup Guide for Claude Code (2025 Edition)

Claude Code is a powerful, terminal-based AI tool from Anthropic that brings agentic workflows and code generation directly to your CLI. If you’re looking to integrate AI seamlessly into your development flow—Claude Code is your new best friend.

💡 This guide walks you through installing, configuring, and using Claude Code from scratch. It also includes solutions for common issues.

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🧰 Prerequisites

Before getting started, ensure you have the following:

• A terminal or command line interface (macOS, Linux, or Windows with WSL)
• Node.js version ≥ 18 (preferably installed via nvm)
• npm package manager
• Access to console.anthropic.com

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⚙️ Step-by-Step Installation

1️⃣ Check Your Node.js Version

If it’s below 18, upgrade using nvm.

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2️⃣ Install Node.js v18+ Using NVM

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3️⃣ Install Claude Code Globally

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4️⃣ Verify Installation

You should see:
1.0.9 (Claude Code) or similar.

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🔐 Authenticate with Anthropic

5️⃣ Login via CLI

You’ll be prompted to enter your Anthropic API key.

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6️⃣ Get Your Anthropic API Key

If you don’t have an API key:

1. Go to console.anthropic.com
2. Sign in or create an account
3. Navigate to API Keys
4. Click “Create Key”
5. Copy the key (starts with sk-ant-)
6. Paste it in when prompted by claude login

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🧪 Test Claude Code with a Prompt

If everything is set up correctly, Claude will output the Python script within seconds.

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🔁 Alternative: Set API Key as Environment Variable

If you prefer not to use claude login, set your API key manually:

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🛠️ Common Issues and Fixes

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✅ Final Check

Try out another prompt to confirm everything is working:

🎉 You’re now ready to build, automate, and accelerate your development with Claude Code.