Get started with Claude

Make your first API call to Claude and build a simple web search assistant

Prerequisites

• An Anthropic Console account
• An API key

Call the API

cURL

1. Set your API key

   Get your API key at the Claude Console and set it as an environment variable:

   export ANTHROPIC_API_KEY='your-api-key-here'
   
2. Make your first API call

   Run this command to create a simple web search assistant:

   curl https://api.anthropic.com/v1/messages \
     -H "Content-Type: application/json" \
     -H "x-api-key: $ANTHROPIC_API_KEY" \
     -H "anthropic-version: 2023-06-01" \
     -d '{
       "model": "claude-sonnet-4-5",
       "max_tokens": 1000,
       "messages": [
         {
           "role": "user", 
           "content": "What should I search for to find the latest developments in renewable energy?"
         }
       ]
     }'
   

   Example output:

   {
     "id": "msg_01HCDu5LRGeP2o7s2xGmxyx8",
     "type": "message", 
     "role": "assistant",
     "content": [
       {
         "type": "text",
         "text": "Here are some effective search strategies to find the latest renewable energy developments:\n\n## Search Terms to Use:\n- \"renewable energy news 2024\"\n- \"clean energy breakthrough\"\n- \"solar/wind/battery technology advances\"\n- \"green energy innovations\"\n- \"climate tech developments\"\n- \"energy storage solutions\"\n\n## Best Sources to Check:\n\n**News & Industry Sites:**\n- Renewable Energy World\n- GreenTech Media (now Wood Mackenzie)\n- Energy Storage News\n- CleanTechnica\n- PV Magazine (for solar)\n- WindPower Engineering & Development..."
       }
     ],
     "model": "claude-sonnet-4-5",
     "stop_reason": "end_turn",
     "usage": {
       "input_tokens": 21,
       "output_tokens": 305
     }
   }
   

Python

1. Set your API key

   Get your API key from the Claude Console and set it as an environment variable:

   export ANTHROPIC_API_KEY='your-api-key-here'
   
2. Install the SDK

   Install the Anthropic Python SDK:

   pip install anthropic
   
3. Create your code

   Save this as quickstart.py:

   import anthropic
   
   client = anthropic.Anthropic()
   
   message = client.messages.create(
       model="claude-sonnet-4-5",
       max_tokens=1000,
       messages=[
           {
               "role": "user",
               "content": "What should I search for to find the latest developments in renewable energy?"
           }
       ]
   )
   print(message.content)
   
4. Run your code

   python quickstart.py
   

   Example output:

   [TextBlock(text='Here are some effective search strategies for finding the latest renewable energy developments:\n\n**Search Terms to Use:**\n- "renewable energy news 2024"\n- "clean energy breakthroughs"\n- "solar/wind/battery technology advances"\n- "energy storage innovations"\n- "green hydrogen developments"\n- "renewable energy policy updates"\n\n**Reliable Sources to Check:**\n- **News & Analysis:** Reuters Energy, Bloomberg New Energy Finance, Greentech Media, Energy Storage News\n- **Industry Publications:** Renewable Energy World, PV Magazine, Wind Power Engineering\n- **Research Organizations:** International Energy Agency (IEA), National Renewable Energy Laboratory (NREL)\n- **Government Sources:** Department of Energy websites, EPA clean energy updates\n\n**Specific Topics to Explore:**\n- Perovskite and next-gen solar cells\n- Offshore wind expansion\n- Grid-scale battery storage\n- Green hydrogen production\n- Carbon capture technologies\n- Smart grid innovations\n- Energy policy changes and incentives...', type='text')]
   

TypeScript

1. Set your API key

   Get your API key from the Claude Console and set it as an environment variable:

   export ANTHROPIC_API_KEY='your-api-key-here'
   
2. Install the SDK

   Install the Anthropic TypeScript SDK:

   npm install @anthropic-ai/sdk
   
3. Create your code

   Save this as quickstart.ts:

   import Anthropic from "@anthropic-ai/sdk";
   
   async function main() {
     const anthropic = new Anthropic();
   
     const msg = await anthropic.messages.create({
       model: "claude-sonnet-4-5",
       max_tokens: 1000,
       messages: [
         {
           role: "user",
           content: "What should I search for to find the latest developments in renewable energy?"
         }
       ]
     });
     console.log(msg);
   }
   
   main().catch(console.error);
   
4. Run your code

   npx tsx quickstart.ts
   

   Example output:

   {
     id: 'msg_01ThFHzad6Bh4TpQ6cHux9t8',
     type: 'message',
     role: 'assistant',
     model: 'claude-sonnet-4-5-20250929',
     content: [
       {
         type: 'text',
         text: 'Here are some effective search strategies to find the latest renewable energy developments:\n\n' +
           '## Search Terms to Use:\n' +
           '- "renewable energy news 2024"\n' +
           '- "clean energy breakthroughs"\n' +
           '- "solar wind technology advances"\n' +
           '- "energy storage innovations"\n' +
           '- "green hydrogen developments"\n' +
           '- "offshore wind projects"\n' +
           '- "battery technology renewable"\n\n' +
           '## Best Sources to Check:\n\n' +
           '**News & Industry Sites:**\n' +
           '- Renewable Energy World\n' +
           '- CleanTechnica\n' +
           '- GreenTech Media (now Wood Mackenzie)\n' +
           '- Energy Storage News\n' +
           '- PV Magazine (for solar)...'
       }
     ],
     stop_reason: 'end_turn',
     usage: {
       input_tokens: 21,
       output_tokens: 302
     }
   }
   

Java

1. Set your API key

   Get your API key from the Claude Console and set it as an environment variable:

   export ANTHROPIC_API_KEY='your-api-key-here'
   
2. Install the SDK

   Add the Anthropic Java SDK to your project. First find the current version on Maven Central.

   Gradle:

   implementation("com.anthropic:anthropic-java:1.0.0")
   

   Maven:

   <dependency>
     <groupId>com.anthropic</groupId>
     <artifactId>anthropic-java</artifactId>
     <version>1.0.0</version>
   </dependency>
   
3. Create your code

   Save this as QuickStart.java:

   import com.anthropic.client.AnthropicClient;
   import com.anthropic.client.okhttp.AnthropicOkHttpClient;
   import com.anthropic.models.messages.Message;
   import com.anthropic.models.messages.MessageCreateParams;
   
   public class QuickStart {
       public static void main(String[] args) {
           AnthropicClient client = AnthropicOkHttpClient.fromEnv();
   
           MessageCreateParams params = MessageCreateParams.builder()
                   .model("claude-sonnet-4-5-20250929")
                   .maxTokens(1000)
                   .addUserMessage("What should I search for to find the latest developments in renewable energy?")
                   .build();
   
           Message message = client.messages().create(params);
           System.out.println(message.content());
       }
   }
   
4. Run your code

   javac QuickStart.java
   java QuickStart
   

   Example output:

   [ContentBlock{text=TextBlock{text=Here are some effective search strategies to find the latest renewable energy developments:
   
   ## Search Terms to Use:
   - "renewable energy news 2024"
   - "clean energy breakthroughs"  
   - "solar/wind/battery technology advances"
   - "energy storage innovations"
   - "green hydrogen developments"
   - "renewable energy policy updates"
   
   ## Best Sources to Check:
   - **News & Analysis:** Reuters Energy, Bloomberg New Energy Finance, Greentech Media
   - **Industry Publications:** Renewable Energy World, PV Magazine, Wind Power Engineering
   - **Research Organizations:** International Energy Agency (IEA), National Renewable Energy Laboratory (NREL)
   - **Government Sources:** Department of Energy websites, EPA clean energy updates
   
   ## Specific Topics to Explore:
   - Perovskite and next-gen solar cells
   - Offshore wind expansion
   - Grid-scale battery storage
   - Green hydrogen production..., type=text}}]
   

Next steps

Now that you have made your first Claude API request, it’s time to explore what else is possible:

Working with Messages

Learn common patterns for the Messages API.

Features Overview

Explore Claude’s advanced features and capabilities.

Client SDKs

Discover Anthropic client libraries.

Claude Cookbook

Learn with interactive Jupyter notebooks.