# Making requests
<a name="making-requests"></a>

Claude Platform on AWS uses the Anthropic Messages API (`/v1/messages`), the same API surface as the Claude first-party platform. The differences are the base URL, the authentication method, and a required `anthropic-workspace-id` header that identifies which [workspace](workspaces.md) the request targets.

 **Shell** 

```
curl "https://aws-external-anthropic.us-west-2.api.aws/v1/messages" \
  --aws-sigv4 "aws:amz:us-west-2:aws-external-anthropic" \
  --user "$AWS_ACCESS_KEY_ID:$AWS_SECRET_ACCESS_KEY" \
  -H "x-amz-security-token: $AWS_SESSION_TOKEN" \
  -H "content-type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-workspace-id: $ANTHROPIC_AWS_WORKSPACE_ID" \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'
```

 **Python** 

```
from anthropic import AnthropicAWS

client = AnthropicAWS()

message = client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}],
)
print(message)
```

 **TypeScript** 

```
import AnthropicAws from "@anthropic-ai/aws-sdk";

const client = new AnthropicAws();

const message = await client.messages.create({
  model: "claude-sonnet-4-6",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello!" }]
});
console.log(message);
```

 **C\#** 

```
using Anthropic;
using Anthropic.Aws;

var client = new AnthropicAwsClient();

var message = await client.Messages.Create(new()
{
    Model = "claude-sonnet-4-6",
    MaxTokens = 1024,
    Messages = [new() { Role = "user", Content = "Hello!" }]
});

Console.WriteLine(message);
```

 **Go** 

```
client, err := anthropicaws.NewClient(context.Background(), anthropicaws.ClientConfig{})
if err != nil {
    panic(err)
}

message, err := client.Messages.New(context.Background(), anthropic.MessageNewParams{
    Model:     anthropic.ModelClaudeSonnet4_6,
    MaxTokens: 1024,
    Messages: []anthropic.MessageParam{
        anthropic.NewUserMessage(anthropic.NewTextBlock("Hello!")),
    },
})
if err != nil {
    panic(err)
}

fmt.Println(message.Content[0].Text)
```

 **Java** 

```
import com.anthropic.aws.backends.AwsBackend;
import com.anthropic.client.AnthropicClient;
import com.anthropic.client.okhttp.AnthropicOkHttpClient;
import com.anthropic.models.messages.Message;
import com.anthropic.models.messages.MessageCreateParams;
import com.anthropic.models.messages.Model;

AnthropicClient client = AnthropicOkHttpClient.builder()
    .backend(AwsBackend.fromEnv())
    .build();

Message message = client.messages().create(
    MessageCreateParams.builder()
        .model(Model.CLAUDE_SONNET_4_6)
        .maxTokens(1024)
        .addUserMessage("Hello!")
        .build()
);

IO.println(message);
```

 **PHP** 

```
use Anthropic\Aws\Client;

$client = new Client();

$message = $client->messages->create(
    model: 'claude-sonnet-4-6',
    maxTokens: 1024,
    messages: [['role' => 'user', 'content' => 'Hello!']],
);

echo $message;
```

 **Ruby** 

```
require "anthropic"

client = Anthropic::AWSClient.new

message = client.messages.create(
  model: "claude-sonnet-4-6",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello!" }]
)

puts message
```

The client reads `AWS_REGION` (or `AWS_DEFAULT_REGION`) and `ANTHROPIC_AWS_WORKSPACE_ID` from the environment. You can override either by passing `aws_region` / `awsRegion` or `workspace_id` / `workspaceId` to the constructor. Both region and workspace ID are required; the constructor throws if either cannot be resolved from these sources.

**Note**  
The `x-amz-security-token` header (curl) is only required for temporary credentials such as IAM roles, SSO, or STS. Omit it when using long-term IAM user credentials. The SDK clients handle this automatically based on the credential source.

The `--aws-sigv4` value follows the format `aws:amz:<region>:<service>`. The SigV4 service name is `aws-external-anthropic`, and the region must match the region in your endpoint URL. A mismatch in either produces a generic signature-rejection error rather than a specific diagnostic.

## Using the base Anthropic client
<a name="_using_the_base_anthropic_client"></a>

If you prefer not to add the AWS SDK dependency, you can use the base `Anthropic` client. This path uses the vanilla SDK environment variable names rather than the `ANTHROPIC_AWS_*` names the dedicated client reads:

```
export ANTHROPIC_API_KEY='your-api-key'
export ANTHROPIC_BASE_URL='https://aws-external-anthropic.us-west-2.api.aws'
export ANTHROPIC_WORKSPACE_ID='your-workspace-id'
```

The Python, TypeScript, and Go SDKs read `ANTHROPIC_API_KEY` and `ANTHROPIC_BASE_URL` automatically; for the other languages, pass them to the constructor. In every language, pass the workspace ID in the `anthropic-workspace-id` header.

 **Python** 

```
import os
from anthropic import Anthropic

client = Anthropic(
    # ANTHROPIC_API_KEY and ANTHROPIC_BASE_URL are read automatically
    default_headers={"anthropic-workspace-id": os.environ["ANTHROPIC_WORKSPACE_ID"]},
)

message = client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}],
)
print(message.content[0].text)
```

 **TypeScript** 

```
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  // ANTHROPIC_API_KEY and ANTHROPIC_BASE_URL are read automatically
  defaultHeaders: { "anthropic-workspace-id": process.env.ANTHROPIC_WORKSPACE_ID }
});

const message = await client.messages.create({
  model: "claude-sonnet-4-6",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello!" }]
});
console.log(message.content);
```