The idea behind Klimper is pretty simple, In theory, but fiendishly complex to execute. To find chords that will work in a musical way with a particular scale or with other chords and to find scales that work well with a specific set of notes. Other apps set out to do similar things, like Jamn, but Klimper moves away from the more traditional circle of fifths approach of other apps and uses a very clean, attractive interface.
And it is very pretty pretty, just one screen is used (a combination of finger swipes brings up options) and all muted pastel shades.
In operation it could not be simpler, chords that fit in with a particular key can be dragged and dropped into a chord sequence and different inversions auditioned. By entering a note sequence the app will give you a range of scales, modes or chords that will fit in. As a compositional tool it is very effective and after 5 minutes with the app I could knock out any number of chord sequences that all sounded very musical and bus entering a few notes from a chord or scale it gave me a range of scales and chords that would fit in well.
It does what it sets out to do very well, and is great fun to use and it genuinely feels useful. A £1.49 IAP gives you midi capability as well. Perhaps the scale notes on the keyboard could be clearer and there could be more information on the music theory behind it all, but the key thing is that I bought this with my own money and have used it everyday since. For the frankly silly £1.49 price, this is a must buy.