Making requests

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 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.

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

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);