Using Claude on AWS Bedrock with Python (boto3)

Call Claude via AWS Bedrock in Python using boto3. Covers bedrock-runtime invoke_model, streaming, IAM setup, and cost comparison vs direct Anthropic API.

AWS Bedrock lets you call Claude models inside your AWS account — no Anthropic API key, no egress to api.anthropic.com, full IAM control. Enterprise teams on HIPAA, FedRAMP, or SOC2 audits often require this path.

Option A — Anthropic SDK's built-in Bedrock client (recommended)

pip install anthropic[bedrock] boto3

import anthropic

# Reads AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY / AWS_REGION from env
# or uses any boto3 credential source (instance profile, SSO, etc.)
client = anthropic.AnthropicBedrock(aws_region="us-east-1")

message = client.messages.create(
    model="anthropic.claude-3-5-sonnet-20241022-v2:0",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Summarize the risks of LLM prompt injection."}]
)
print(message.content[0].text)

AnthropicBedrock uses the same interface as anthropic.Anthropic — you can swap the client and keep the rest of your code identical.

Option B — raw boto3 (no Anthropic SDK dependency)

import boto3, json

bedrock = boto3.client("bedrock-runtime", region_name="us-east-1")

payload = {
    "anthropic_version": "bedrock-2023-05-31",
    "max_tokens": 512,
    "messages": [{"role": "user", "content": "What is AWS Bedrock?"}]
}

response = bedrock.invoke_model(
    modelId="anthropic.claude-3-5-haiku-20241022-v1:0",
    body=json.dumps(payload),
    contentType="application/json",
    accept="application/json"
)

body = json.loads(response["body"].read())
print(body["content"][0]["text"])

Streaming via boto3

import boto3, json

bedrock = boto3.client("bedrock-runtime", region_name="us-east-1")

payload = {
    "anthropic_version": "bedrock-2023-05-31",
    "max_tokens": 2048,
    "messages": [{"role": "user", "content": "Write a detailed security threat model."}]
}

response = bedrock.invoke_model_with_response_stream(
    modelId="anthropic.claude-3-5-sonnet-20241022-v2:0",
    body=json.dumps(payload),
    contentType="application/json",
    accept="application/json"
)

for event in response["body"]:
    chunk = json.loads(event["chunk"]["bytes"])
    if chunk.get("type") == "content_block_delta":
        print(chunk["delta"].get("text", ""), end="", flush=True)
print()

IAM policy (minimal)

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": [
      "bedrock:InvokeModel",
      "bedrock:InvokeModelWithResponseStream"
    ],
    "Resource": "arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-3-5-sonnet-20241022-v2:0"
  }]
}

Bedrock vs direct Anthropic API

For cost estimation across Bedrock and direct API, paste your token counts into the Claude API Cost Calculator. For authentication patterns when using the direct API, see the Anthropic API authentication guide.

Frequently asked questions

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