Front end or back end ajax call for another url

I am making an Emberjs application which would parse podcast's rss feed.

In application you can add urls of rss feeds then the app would parse it and create a nice interface to listen to your favourite feeds.

My question is that where should i make the AJAX call, on the backend or on the frontend? Because right now i store the url-s on the backend and i send them down to the client side then i make ajax calls on the frontend and then parse the urls.

Which is better practice? Making calls on backend or on frontend?