Send as POST adds an option for sharing to photos and web pages. You can share to any URL you want via a POST request. Sharing via Send as POST will create a POST request with these parameters:
For photos:
"image": the image data
"caption" (optional): the text provided in the share card.
For links:
"url": the URL of the page
"quote" (optional): the highlighted text on the page, if any
"comment" (optional): the text added in the sharing card, if any
"title" (optional): the text specified in the title field of the sharing card, if any. Defaults to the title of the page being shared
Additional parameters, e.g. a shared secret, can be configured in the app. They will be sent with each POST request.