Files API

The Files API lets you upload and manage files to use with the Claude API without re-uploading content with each request. This is particularly useful when using the code execution tool to provide inputs (e.g. datasets and documents) and then download outputs (e.g. charts). You can also use the Files API to prevent having to continually re-upload frequently used documents and images across multiple API calls. You can explore the API reference directly, in addition to this guide.

Supported models

Referencing a file_id in a Messages request is supported in all models that support the given file type. For example, images are supported in all Claude 3+ models, PDFs in all Claude 3.5+ models, and various other file types for the code execution tool in Claude Haiku 4.5 plus all Claude 3.7+ models.

The Files API is currently not supported on Amazon Bedrock or Google Vertex AI.

How the Files API works

The Files API provides a simple create-once, use-many-times approach for working with files:

• Upload files to our secure storage and receive a unique file_id
• Download files that are created from skills or the code execution tool
• Reference files in Messages requests using the file_id instead of re-uploading content
• Manage your files with list, retrieve, and delete operations

How to use the Files API

Uploading a file

Upload a file to be referenced in future API calls:

curl -X POST https://api.anthropic.com/v1/files \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14" \
  -F "file=@/path/to/document.pdf"

The response from uploading a file will include:

{
  "id": "file_011CNha8iCJcU1wXNR6q4V8w",
  "type": "file",
  "filename": "document.pdf",
  "mime_type": "application/pdf",
  "size_bytes": 1024000,
  "created_at": "2025-01-01T00:00:00Z",
  "downloadable": false
}

Using a file in messages

Once uploaded, reference the file using its file_id:

curl -X POST https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 1024,
    "messages": [
      {
        "role": "user",
        "content": [
          {
            "type": "text",
            "text": "Please summarize this document for me."          
          },
          {
            "type": "document",
            "source": {
              "type": "file",
              "file_id": "file_011CNha8iCJcU1wXNR6q4V8w"
            }
          }
        ]
      }
    ]
  }'

File types and content blocks

The Files API supports different file types that correspond to different content block types:

Working with other file formats

For file types that are not supported as document blocks (.csv, .txt, .md, .docx, .xlsx), convert the files to plain text, and include the content directly in your message:

# Example: Reading a text file and sending it as plain text
# Note: For files with special characters, consider base64 encoding
TEXT_CONTENT=$(cat document.txt | jq -Rs .)

curl https://api.anthropic.com/v1/messages \
  -H "content-type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d @- <<EOF
{
  "model": "claude-sonnet-4-5",
  "max_tokens": 1024,
  "messages": [
    {
      "role": "user",
      "content": [
        {
          "type": "text",
          "text": "Here's the document content:\n\n${TEXT_CONTENT}\n\nPlease summarize this document."
        }
      ]
    }
  ]
}
EOF

Document blocks

For PDFs and text files, use the document content block:

{
  "type": "document",
  "source": {
    "type": "file",
    "file_id": "file_011CNha8iCJcU1wXNR6q4V8w"
  },
  "title": "Document Title", // Optional
  "context": "Context about the document", // Optional  
  "citations": {"enabled": true} // Optional, enables citations
}

Image blocks

For images, use the image content block:

{
  "type": "image",
  "source": {
    "type": "file",
    "file_id": "file_011CPMxVD3fHLUhvTqtsQA5w"
  }
}

Managing files

List files

Retrieve a list of your uploaded files:

curl https://api.anthropic.com/v1/files \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14"

Get file metadata

Retrieve information about a specific file:

curl https://api.anthropic.com/v1/files/file_011CNha8iCJcU1wXNR6q4V8w \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14"

Delete a file

Remove a file from your workspace:

curl -X DELETE https://api.anthropic.com/v1/files/file_011CNha8iCJcU1wXNR6q4V8w \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14"

Downloading a file

Download files that have been created by skills or the code execution tool:

curl -X GET "https://api.anthropic.com/v1/files/file_011CNha8iCJcU1wXNR6q4V8w/content" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "anthropic-beta: files-api-2025-04-14" \
  --output downloaded_file.txt

File storage and limits

Storage limits

• Maximum file size: 500 MB per file
• Total storage: 100 GB per organization

File lifecycle

• Files are scoped to the workspace of the API key. Other API keys can use files created by any other API key associated with the same workspace
• Files persist until you delete them
• Deleted files cannot be recovered
• Files are inaccessible via the API shortly after deletion, but they may persist in active Messages API calls and associated tool uses
• Files that users delete will be deleted in accordance with our data retention policy.

Error handling

Common errors when using the Files API include:

• File not found (404): The specified file_id doesn't exist or you don't have access to it
• Invalid file type (400): The file type doesn't match the content block type (e.g., using an image file in a document block)
• Exceeds context window size (400): The file is larger than the context window size (e.g. using a 500 MB plaintext file in a /v1/messages request)
• Invalid filename (400): Filename doesn't meet the length requirements (1-255 characters) or contains forbidden characters (<, >, :, ", |, ?, *, \, /, or unicode characters 0-31)
• File too large (413): File exceeds the 500 MB limit
• Storage limit exceeded (403): Your organization has reached the 100 GB storage limit

{
  "type": "error",
  "error": {
    "type": "invalid_request_error",
    "message": "File not found: file_011CNha8iCJcU1wXNR6q4V8w"
  }
}

Usage and billing

File API operations are free:

• Uploading files
• Downloading files
• Listing files
• Getting file metadata
• Deleting files

File content used in Messages requests are priced as input tokens. You can only download files created by skills or the code execution tool.

Rate limits

During the beta period:

• File-related API calls are limited to approximately 100 requests per minute
• Contact us if you need higher limits for your use case