Amazon has launched a new HTML5 mobile web store for its library of 22 million MP3 tracks that’s specifically optimized for iPhone and iPod touch, the company announced today.

Amazon made the move to challenge Apple’s claim as the largest and most popular seller of digital music through the iTunes store. With several 69-cent singles and $5 album deals, Amazon is already undercutting Apple on price, so now it’s just a matter of making people buy from a mobile website rather than the iTunes app.

Purchases made through Amazon’s new mobile web store won’t be subject to the 30 percent fee Apple charges for all purchases made through an iOS app. (So, Amazon could actually make money off of music purchases, which wouldn’t be possible if it went through Apple.)

As for the mobile web store, it has a slick design that’s responsive to touch-based controls — meaning you can swipe back and forth to see a selection of albums and such. All purchases are immediately available on Amazon’s Cloud music player, which you can download for any iOS device.