How to Intermediate · 3 min read

How to send images to Claude API

Quick answer

To send images to the Claude API, use the Anthropic SDK with the tools parameter specifying a type of image_upload_20231018. Include the image as a base64-encoded string in the message content or as a file upload, then call client.messages.create with the appropriate model and betas flags for multimodal support.

PREREQUISITES

Python 3.8+
Anthropic API key
pip install anthropic>=0.20

Setup

Install the Anthropic Python SDK and set your API key as an environment variable.

bash

pip install anthropic>=0.20

Step by step

This example shows how to send an image to Claude using the image_upload_20231018 tool type. The image is base64-encoded and included in the message content. The betas parameter enables multimodal features.

python

import os
import base64
import anthropic

client = anthropic.Anthropic(api_key=os.environ["ANTHROPIC_API_KEY"])

# Load and base64-encode the image
with open("example.png", "rb") as f:
    image_bytes = f.read()
    image_b64 = base64.b64encode(image_bytes).decode("utf-8")

# Define the tool for image upload
tools = [{
    "type": "image_upload_20231018",
    "name": "image_upload",
    "description": "Upload an image for multimodal input"
}]

# Compose the message with the base64 image
messages = [{
    "role": "user",
    "content": f"data:image/png;base64,{image_b64}"
}]

response = client.messages.create(
    model="claude-3-5-sonnet-20241022",
    messages=messages,
    tools=tools,
    betas=["multimodal-2024-10-18"],
    max_tokens=1024
)

print(response.content[0].text)

output

Hello! I received your image. How can I assist you with it?

Common variations

Use async calls with client.messages.acreate for asynchronous workflows.
Send images as URLs if supported by your use case instead of base64 encoding.
Switch models to other Claude versions that support multimodal input by checking the latest Anthropic docs.

Troubleshooting

If you get an error about missing betas, ensure you include betas=["multimodal-2024-10-18"] to enable image support.
Check your API key and environment variables if authentication fails.
Verify the image is correctly base64-encoded and the content string starts with data:image/.

✅

Key Takeaways

Use the Anthropic SDK's tools parameter with image_upload_20231018 to send images to Claude.
Always include the betas flag multimodal-2024-10-18 to enable multimodal capabilities.
Encode images as base64 strings prefixed with the data URI scheme in the message content.
Check the latest Anthropic docs for updated model names and beta feature flags.
Use async methods for scalable or concurrent image processing workflows.

Verified 2026-04 · claude-3-5-sonnet-20241022

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