SASRip has a free API you can use to download files however you want.
Only restriction is that you may not use it commercially.
All personal use is fair game.
SASRip is using youtube-dl as it's back-bone.
So the API supports all download services that youtube-dl supports.
You can make an API call over at:/api/DownloadAPI/v1.0/video/
Your POST request must contain a JSON Body with "DownloadURL" as a key and the link to the video/audio as the value.
You will then have to await a JSON response, containing the following Key-Value Pairs:Success - Boolean, if the video/audio extraction was successful.
DownloadPath - String, the URL to your file, use if Success is true.
Status - String, file_ready, file_processing or file_not_found.