December 30, 2025 | Composio Docs

Binary Data Support for Proxy Execute

The /api/v3/tools/execute/proxy endpoint now supports binary data for both file uploads and downloads.

File Uploads (`binary_body`)

To upload a file via the proxy, use the binary_body field in your request payload. This supports two approaches: specifying either a URL pointing to the file or providing the base64-encoded content directly.

Upload File via URL

$ curl --location 'https://backend.composio.dev/api/v3/tools/execute/proxy' \
>   --header 'accept: application/json' \
>   --header 'x-api-key: <YOUR_API_KEY>' \
>   --header 'Content-Type: application/json' \
>   --data '{
>     "endpoint": "/upload-endpoint",
>     "method": "POST",
>     "connected_account_id": "<CONNECTED_ACCOUNT_ID>",
>     "binary_body": {
>       "url": "{URL_TO_THE_FILE}"
>     }
>   }'

Upload File via Base64 Content

Supported up to 4MB file size.

$ curl --location 'https://backend.composio.dev/api/v3/tools/execute/proxy' \
>   --header 'accept: application/json' \
>   --header 'x-api-key: <YOUR_API_KEY>' \
>   --header 'Content-Type: application/json' \
>   --data '{
>     "endpoint": "/upload-endpoint",
>     "method": "POST",
>     "connected_account_id": "<CONNECTED_ACCOUNT_ID>",
>     "binary_body": {
>       "base64": "JVBERi0xLjQKJ...<base64_data>...",
>       "content_type": "application/pdf"
>     }
>   }'

File Downloads (`binary_data`)

When the proxied request returns a binary response (for example, a PDF or image), the proxy automatically uploads the file to temporary storage, and you receive a signed URL in the binary_data field. This enables you to download large files securely.

File Download Request

$ curl --location 'https://backend.composio.dev/api/v3/tools/execute/proxy' \
>   --header 'accept: application/json' \
>   --header 'x-api-key: <YOUR_API_KEY>' \
>   --header 'Content-Type: application/json' \
>   --data '{
>     "endpoint": "{YOUR_ENDPOINT}",
>     "method": "GET",
>     "connected_account_id": "{YOUR_CONNECTED_ACCOUNT_ID}"
>   }'

File Download Response

1 {
2   "data": {},
3   "binary_data": {
4     "url": "url to the file",
5     "content_type": "content type of the file",
6     "size": "size of the file",
7     "expires_at": "expires at of the file"
8   },
9   "status": "status code of the response",
10   "headers": "headers of the response"
11 }

Summary

Feature	Field	Description
File Upload via URL	`binary_body.url`	Provide a URL pointing to the file to upload
File Upload via Base64	`binary_body.base64` + `binary_body.content_type`	Provide base64-encoded content (up to 4MB)
File Download	`binary_data` in response	Receive a signed URL to download binary responses

We’d love your feedback on the new proxy execute capabilities. If anything feels unclear or you have suggestions for improvement, please reach out.