How to Use the Claude 3.7 Sonnet API: Developer Guide

Anthropic has introduced Claude 3.7 Sonnet, its most advanced AI model, designed to offer flexible reasoning capabilities. Unlike previous models that required separate configurations for different types of queries, Claude 3.7 integrates both fast response and extended thinking into a single model. This allows users to dynamically adjust how the model processes requests based on their needs, balancing speed and depth.

One of the most significant advancements in Claude 3.7 is its improved performance in coding, logic, and mathematical reasoning. It outperforms previous versions in real-world software development tasks, making it a powerful assistant for programmers and engineers. Additionally, it introduces a budget-controlled thinking feature, enabling API users to specify how much processing power is allocated to a query. This helps in managing both response time and costs effectively.

Claude 3.7 is available on all Claude API plans, as well as Amazon Bedrock and Google Cloud's Vertex AI. The pricing remains the same as previous versions: $3 per million input tokens and $15 per million output tokens, which also includes extended thinking tokens. The ability to control how long the model "thinks" makes this model particularly useful for tasks requiring both efficiency and accuracy.

This guide will cover setting up the Claude 3.7 API, generating an API key, and making API requests using cURL, Python, and JavaScript SDK.

New Features

Claude 3.7 Sonnet introduces several improvements over previous versions:

• Hybrid reasoning for both fast responses and extended thinking.
• Budget-controlled processing, allowing users to limit thinking tokens.
• Enhanced coding and debugging capabilities, making it an excellent tool for software engineers.
• Strong performance in logic, mathematics, and instruction-following tasks
• Same pricing structure as previous Claude models: $3 per million input tokens and $15 per million output tokens.

Getting Started

Step 1: Generate an API Key

To use the Claude 3.7 API, you need an API key. Follow these steps to get started:

1. Visit the Anthropic Console keys page.
2. Login or create an account if you don't have one.
3. Generate an API key and copy it for your applications.

Making API Requests

Claude 3.7 Sonnet supports API requests through cURL, Python, and JavaScript. Below are examples for each.

1. Using cURL

To quickly test the Claude API, use the following cURL command:

curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data '{
         "model": "claude-3-7-sonnet-20250219",
         "max_tokens": 1024,
         "messages": [
             {"role": "user", "content": "Hello, world"}
         ]
     }'

Replace $ANTHROPIC_API_KEY with your own Anthropic API key.

Response:

{
  "id": "<id>",
  "type": "message",
  "role": "assistant",
  "model": "claude-3-7-sonnet-20250219",
  "content": [
    {
      "type": "text",
      "text": "Hello! How can I assist you today? Whether you have a question, need information, or just want to chat, I'm here to help. What's on your mind?"
    }
  ],
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 10,
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "output_tokens": 39
  }
}

2. Using Python (SDK)

First, install the anthropic SDK:

pip install anthropic

Then, use the following Python script to send a request:

import anthropic

client = anthropic.Anthropic(
    # defaults to os.environ.get("ANTHROPIC_API_KEY")
    api_key="your_api_key",  # Replace with your actual API key
)

response = client.messages.create(
    model="claude-3-7-sonnet-20250219",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello, world"}
    ]
)

print(response.content[0].text)

3. Using JavaScript (Node.js)

To integrate with JavaScript, install the @anthropic-ai/sdk package:

npm install @anthropic-ai/sdk

Use this script to make a request:

const { Anthropic } = require('@anthropic-ai/sdk');

const anthropic = new Anthropic({
    // defaults to process.env["ANTHROPIC_API_KEY"]
    apiKey: 'your_api_key', 
});

// Wrap the async code in a function
async function main() {
    const response = await anthropic.messages.create({
        model: "claude-3-7-sonnet-20250219",
        max_tokens: 1024,
        messages: [
            { "role": "user", "content": "Hello, world" }
        ]
    });

    console.log(response.content[0].text)
}

main().catch(console.error);

Conclusion

Claude 3.7 Sonnet is a powerful, flexible AI model that enhances coding, logical reasoning, and decision-making. It provides scalable and efficient API interactions whether you integrate it into business applications, development workflows, or research projects.

With cURL, Python, and JavaScript SDK support, getting started with the Claude API is straightforward.

For more details, visit the official Anthropic API documentation.