What is Deezer? Deezer is a music streaming app that gives you access to over 90 million tracks worldwide and other audio content like podcasts. You even get curated recommendations and Deezer Originals exclusives.What is Deezer? Deezer is a music streaming app that gives you access to over 90 million tracks worldwide and other audio content like podcasts. You even get curated recommendations and Deezer Originals exclusives.