These are some Dropbox API requests that I have tested and found working:
Get Access token
POST https://api.dropbox.com/oauth2/token?grant_type=refresh_token&refresh_token=<REFRESH_TOKEN>&client_secret=<CLIENT_SECRET>
Use the refresh token generated through the Dropbox API app. Since the refresh token has an expiry of up to a few months it can be reused to generate an access token.
Get a temporary link to the file
To generate Dropbox file links with a limited expiry time. This is a secure way if you want to generate a temporary link.
POST https://api.dropboxapi.com/2/files/get_temporary_link
Body: {“path”:<RELATIVE_PATH_INSIDE_DROPBOX>}
Headers:
Dropbox-API-Path-Root: { “.tag”: “root”, “root”: <ROOT_FOLDER_ID_FROM_DROPBOX_APP> }
Authorization: Bearer <ACCESS_TOKEN>
Download a file
POST https://content.dropboxapi.com/2/files/download
Headers
Authorization: Bearer <ACCESS_TOKEN>
Dropbox-API-Arg: {“path”:<RELATIVE_PATH>}
Dropbox-API-Path-Root: { “.tag”: “root”, “root”: <ROOT_FOLDER_ID_FROM_DROPBOX_APP> }