Using Anthropic File API with LiteLLM Proxy

Overview

This tutorial shows how to create and analyze files with Claude-4 on Anthropic via LiteLLM Proxy.

Prerequisites

• LiteLLM Proxy running
• Anthropic API key

Add the following to your .env file:

ANTHROPIC_API_KEY=sk-<your-api-key>

Usage

1. Setup config.yaml

model_list:
  - model_name: claude-opus
    litellm_params:
      model: anthropic/claude-opus-5
      api_key: os.environ/ANTHROPIC_API_KEY

2. Create a file

Use the /anthropic passthrough endpoint to create a file.

curl -L -X POST 'http://0.0.0.0:4000/anthropic/v1/files' \
-H "x-api-key: $LITELLM_API_KEY" \
-H 'anthropic-version: 2023-06-01' \
-H 'anthropic-beta: files-api-2025-04-14' \
-F 'file=@"/path/to/your/file.csv"'

Expected response:

{
  "created_at": "2023-11-07T05:31:56Z",
  "downloadable": false,
  "filename": "file.csv",
  "id": "file-1234",
  "mime_type": "text/csv",
  "size_bytes": 1,
  "type": "file"
}

3. Analyze the file with Claude-4 via /chat/completions

curl -L -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
-H 'Content-Type: application/json' \
-H "Authorization: Bearer $LITELLM_API_KEY" \
-d '{
    "model": "claude-opus",
    "messages": [
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "What is in this sheet?"},
                {
                    "type": "file",
                    "file": {
                        "file_id": "file-1234",
                        "format": "text/csv" # 👈 IMPORTANT: This is the format of the file you want to analyze
                    }
                }
            ]
        }
    ]
}'