DJ applications aren't anything new, but recently, algoriddim GmbH has teamed up with Spotify to open the floodgates for DJs—amateurs and pros alike. The partnership will bring Spotify's 20 million+ tracks to your fingertips while mixing, and also help introduce you and your listeners to new music.
Djay 2 is free for iPhone and currently half off ($4.99) for iPads. Stop creating horrible, off-beat mixes by using Djay to help match BPMs and pitches. Djay will also help offer suggestions based on currently playing songs, and even automix it for you lazy DJs while you grab a drink or two.
For pros, you just got a huge bump in your music catalogue. For aspiring and upcoming DJs, you just got a lot more music to mess with.