Navichord, from Denis Kutuzov, was originally released back in September 2014 but it continues to see regular updates. They aren't always worth showcasing here, but the sheer consistency of these updates is definitely noteworthy. The AppDB listing doesn't even go back far enough to show them all, but you can see 12 updates in the last year! Not bad for an app that was originally launched almost 4 years ago.
What's new in Navichord v2.6.8:IAA transport and clock disable options
Keep chord voicing for all picker columns
New AutoScale mode - change root keeping current scale
Minor UX update to match iPhone app