Movable Do system is very effective to develop your solfege technique. Because if you can feel music with movable Do in any key, you will be able to imagine functions of each scale degree. And this application also helps you to understand why the double sharp and double flat exist.

MovableDo alternatives

Better Ears Beginner - Music and Ear Training

Better Ears Beginner, is the free version of Better Ears, an educational Music Theory and Ear Training app, which helps you grow your musical skills and enhance your hearing capabilities. There are 13 different exercises included, starting from interval recognition all the way to chord progressions - Better Ears Beginner has all the features of Better Ears, but is limited to one level and does not offer custom exercises. If a relevant article is not available online, another topically-appropriate article will be shown instead.