Get started with Claude

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

Prerequisites

An Anthropic Console account

Call the API

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'
```
To persist the key across shell sessions, add the line to your shell profile (such as ~/.zshrc or ~/.bashrc).

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-opus-4-7",
    "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-opus-4-7",
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 21,
    "output_tokens": 305
  }
}

Install the CLI
Install the Anthropic CLI with Homebrew:
```
brew install anthropics/tap/ant
```
For other installation methods, see Installation in the CLI reference.
Authenticate
Log in with your Anthropic account:
```
ant auth login
```
This opens a browser-based OAuth flow. After authorizing, confirm your credential with:
```
ant auth status
```
On a remote host without a browser, pass --no-browser to get a URL you can open on another device, then paste the returned code back into the terminal. If ANTHROPIC_API_KEY is set in your environment, it takes precedence over the login credentials. For non-interactive environments such as CI, see Authentication.

Make your first API call

Run this command to create a simple web search assistant:

ant messages create \
  --model claude-opus-4-7 \
  --max-tokens 1000 \
  --message '{
    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-opus-4-7",
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 21,
    "output_tokens": 305
  }
}

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'
```
To persist the key across shell sessions, add the line to your shell profile (such as ~/.zshrc or ~/.bashrc).
Install the SDK
Install the Anthropic Python SDK:
```
pip install anthropic
```

Create your code

Save this as quickstart.py:

import anthropic

client = anthropic.Anthropic()

message = client.messages.create(
    model="claude-opus-4-7",
    max_tokens=1000,
    messages=[
        {
            "role": "user",
            "content": "What should I search for to find the latest developments in renewable energy?",
        }
    ],
)
print(message.content)

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",
    )
]

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'
```
To persist the key across shell sessions, add the line to your shell profile (such as ~/.zshrc or ~/.bashrc).
Install the SDK
Install the Anthropic TypeScript SDK:
```
npm install @anthropic-ai/sdk
```

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-opus-4-7",
    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);

Run your code

npx tsx quickstart.ts

Example output:

const _ =
  // output
  {
    id: "msg_01ThFHzad6Bh4TpQ6cHux9t8",
    type: "message",
    role: "assistant",
    model: "claude-opus-4-7",
    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
    }
  }

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'
```
To persist the key across shell sessions, add the line to your shell profile (such as ~/.zshrc or ~/.bashrc).

Set up your project

You need a JDK (25 or later) and either Gradle or Maven on your PATH. Create a directory for your project with a Java source directory inside it:

mkdir -p claude-quickstart/src/main/java && cd claude-quickstart

Then add a build file. Find the current SDK version on Maven Central.

Save this as build.gradle.kts:

plugins {
    application
}

repositories {
    mavenCentral()
}

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(25)
    }
}

dependencies {
    implementation("com.anthropic:anthropic-java:2.33.0")
}

application {
    mainClass = "QuickStart"
}

Save this as pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example</groupId>
  <artifactId>quickstart</artifactId>
  <version>1.0-SNAPSHOT</version>
  <properties>
    <maven.compiler.release>25</maven.compiler.release>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <dependencies>
    <dependency>
      <groupId>com.anthropic</groupId>
      <artifactId>anthropic-java</artifactId>
      <version>2.33.0</version>
    </dependency>
  </dependencies>
</project>

Create your code

Save this as QuickStart.java in your project's Java source directory (usually src/main/java/):

import com.anthropic.client.okhttp.AnthropicOkHttpClient;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Model;

static void main() {
    var client = AnthropicOkHttpClient.fromEnv();

    var params = MessageCreateParams.builder()
        .model(Model.CLAUDE_OPUS_4_7)
        .maxTokens(1000)
        .addUserMessage(
            "What should I search for to find the latest developments in renewable energy?"
        )
        .build();

    Message message = client.messages().create(params);
    IO.println(message.content());
}

Run your code

gradle run

mvn compile exec:java -Dexec.mainClass=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

You made your first API call. Next, learn the Messages API patterns you'll use in every Claude integration.

◆Working with the Messages API

Learn multi-turn conversations, system prompts, stop reasons, and other core patterns.

Once you're comfortable with the basics, explore further:

◆Models overview

Compare Claude models by capability and cost.

◆Features overview

Browse all Claude capabilities: tools, context management, structured outputs, and more.

◆Client SDKs

Reference documentation for Python, TypeScript, Java, and other client libraries.

Get started with Claude

Prerequisites

Call the API

Set your API key

Make your first API call

Install the CLI

Authenticate

Make your first API call

Set your API key

Install the SDK

Create your code

Run your code

Set your API key

Install the SDK

Create your code

Run your code

Set your API key

Set up your project

Create your code

Run your code

Next steps