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API Key Setup

What you'll learn in this chapter: How to get an API key, configure it securely, and choose the right pricing plan

Prerequisites

You should complete the Installation Guide first.

What Is an API Key?​

An API key is an authentication credential for accessing the Claude AI service. Claude Code uses it to communicate with Anthropic's servers.

Important

Never upload your API key to a public repository (e.g., GitHub). If it leaks, unauthorized charges may be incurred.

How to Get an API Key​

Step 1: Go to the Anthropic Console​

Visit console.anthropic.com and sign up or log in.

Step 2: Navigate to the API Keys Menu​

In the left sidebar, click API Keys.

Step 3: Create a New API Key​

Click Create Key, enter a name (e.g., claude-code-personal), and click Create Key.

Step 4: Copy the API Key​

Copy the generated key (sk-ant-api03-...). You won't be able to see it again after leaving this page, so store it somewhere safe.

How to Configure the API Key​

An API key prompt appears on first launch.

claude
# Paste your key and press Enter

Method 2: Set as an Environment Variable​

export ANTHROPIC_API_KEY="sk-ant-api03-..."
claude

Method 3: Save Permanently in Your Shell Profile​

macOS (zsh, the default shell):

echo 'export ANTHROPIC_API_KEY="sk-ant-api03-..."' >> ~/.zshrc
source ~/.zshrc

macOS/Linux (bash):

echo 'export ANTHROPIC_API_KEY="sk-ant-api03-..."' >> ~/.bashrc
source ~/.bashrc

Windows PowerShell:

[System.Environment]::SetEnvironmentVariable("ANTHROPIC_API_KEY", "sk-ant-api03-...", "User")

Understanding Pricing​

Claude Code uses the Anthropic API, so costs are incurred based on usage.

Pricing Tiers (as of 2026)​

ModelPriceCharacteristics
Claude HaikuLowFast, suited for simple tasks
Claude SonnetMediumBalanced, default model
Claude OpusHighBest performance

For exact pricing, check the Anthropic pricing page.

Typical Usage Examples​

For a typical 30-minute development session:

  • Small bug fix: $0.01 -- $0.05
  • New feature implementation: $0.10 -- $0.50
  • Large-scale refactoring: $0.50 -- $2.00

Cost Management Tips​

  1. Set a spending limit: Console -> Settings -> Limits to set a monthly cap
  2. Use the Haiku model: For simple tasks, switch to Haiku (/model claude-haiku-4-5-20251001)
  3. Leverage caching: Prompt caching can save up to 90% on repeated context

Getting Started for Free​

Claude.ai Subscribers (Max Plan)​

Claude.ai Max subscribers can use Claude Code at no additional cost.

claude
# Select the "Login with Claude.ai" option

API Credits​

You can register a card on the Anthropic Console and start with a minimum of $5 in credits.

Security Best Practices​

Make sure to add these to your .gitignore:

.env
*.env

Never do the following:

  • Hardcode API keys in your source code
  • Upload keys to public repositories on GitHub, GitLab, etc.

If your key is compromised:

  1. Immediately go to Console -> API Keys -> Deactivate the key
  2. Generate a new key
  3. Replace the key in all environments

Key Takeaways​

  • Get your API key from console.anthropic.com
  • Setting it via the ANTHROPIC_API_KEY environment variable is the safest approach
  • Costs are usage-based -- setting a monthly limit is recommended
  • Claude.ai Max plan subscribers pay no additional cost

Next Step​

IDE Integration -- Learn how to use Claude Code more conveniently with VS Code and JetBrains

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