Smart Karaoke: Everysing Sing! is an app that lets you do karaoke alone as well as with a friend in a lovely duet. To do a duet, you'll need to be registered, but you can sing alone without registering.
Before you start singing, you can choose if you want to sing without being recorded or sing it and record your performance. If you opt for the second option, you can choose whether you want to record your performance with video, using your smartphone's camera, or just audio. Once you're done singing, you can also share the video on your account.
The Smart Karaoke: Everysing Sing! catalog includes all kinds of songs: for male voices, female voices, and, of course, for duets. As is typical for this kind of app, you can save any song you like to your favorites for easy access.
Smart Karaoke: Everysing Sing! is an excellent karaoke app with a ton of different songs and some very interesting features.