Claude Token Usage Tracker

A simple Node.js application that makes a test call to Claude AI and displays the token usage statistics.

Prerequisites

• Node.js (v18 or higher)
• An Anthropic API key

Setup Instructions

1. Install Dependencies

First, navigate to your project directory and install the required packages:

npm install

This will install:

• @anthropic-ai/sdk - The Anthropic API client
• dotenv - For environment variable management

2. Configure Your API Key

Create a .env file in the project root and add your Anthropic API key:

ANTHROPIC_API_KEY=your-actual-api-key-here

To get your API key:

1. Go to https://console.anthropic.com/
2. Sign up or log in
3. Navigate to "API Keys" in the settings
4. Create a new API key
5. Copy and paste it into your .env file

Important: Never commit your .env file to version control. It's already included in .gitignore.

Running the Application

While in the project root, execute the script with:

node src/index.js

What It Does

The application will:

1. Send a test prompt to Claude (Claude Sonnet 4.5)
2. Receive a response
3. Display the response text
4. Show token usage statistics:
   • Input tokens (tokens in your prompt)
   • Output tokens (tokens in Claude's response)
   • Total tokens used

Example Output

🤖 Making a test call to Claude...

📝 Response: The International Space Station travels at about 17,500 miles per hour, completing an orbit around Earth every 90 minutes.

📊 Token Usage:
   Input tokens:  15
   Output tokens: 28
   Total tokens:  43

Customizing the Prompt

To test with different prompts, edit the prompt in src/index.js:

const result = await callLLM("Your custom prompt here");

File Structure

project-root/
├── package.json          # Node.js dependencies and scripts
├── .env                  # Your API key (not in git)
├── .gitignore           # Files to ignore in git
├── README.md            # This file
└── src/
    ├── index.js         # Main entry point
    └── llmCall.js       # LLM API call handler

Troubleshooting

"Cannot find module '@anthropic-ai/sdk'"

Run npm install to install dependencies.

"Error: Missing required parameter: 'apiKey'"

Make sure your .env file exists and contains a valid API key.

"401 Unauthorized"

Your API key may be invalid or expired. Generate a new one from the Anthropic console.

API Costs

Each API call uses tokens and costs money based on Anthropic's pricing. Monitor your usage at https://console.anthropic.com/

Current pricing (as of January 2025):

• Claude Sonnet 4.5: Check https://www.anthropic.com/pricing for latest rates