Spotify is a digital music service with a significant database of songs.
Marfeel uses the embedded iframe feature to display Spotify links.
To implement the Spotify extension, Marfeel copies the iframe on the frontend along with its source and the data-href attribute.
On the backend, Marfeel inspects if the source of the iframe identified in an article is in the allowed sources. If it is, Marfeel displays the iframe on the frontend.
The iframe's source is only loaded when it's inside the viewport.