Data URL via a JSON POST to a Temporary Upload Link - Composition Help

When uploading to a "/apitul" link like this, the file data to upload needs to be sent in the HTTPS request body as "application/octet-stream". Exactly how you do that will depend on your scenario and the client you're using (curl, in this case).

For example, with curl, you can use curl's "--data-binary" parameter to supply the data to send, with the "@filename" syntax to specify a local file. 

You mentioned that you just have a URL to the file though, as opposed to having it on the local filesystem, so you probably can't use that parameter exactly like that. You'll need to work out how to get the contents of the data at that URL into the request body. That would be more of a question for using curl itself though, so I can't offer too much support for that, as that's not made by Dropbox. The lack of a name and extension on the source URL itself wouldn't matter though, as the destination path is set by the initial call to /2/files/get_temporary_upload_link anyway.

And regarding using the URL directly with /2/files/save_url, are you referring to using large URL that starts with "data:" specifically? That wouldn't be officially supported unfortunately. Otherwise, please share a sample and I'll be happy to look into why it's failing.