Do one thing. Do it really well. Repeat.

I’ve tangled with every GTD app there is. I’ve wrestled with setting repeating tasks in iCal. I didn’t know it, at least not beyond a certain inchoate longing, but what I wanted was something that didn’t hogtie me with complexity. I wanted something that would live in my pocket and execute simple reminders with deadly efficiency and an absolute minimum of fuss. What I was looking for was Due, “the missing reminder app” for iPhone.

I understand the impulse to bulk up a smartphone with pre-installed apps, and the impulse to make those apps Swiss Army knives. But I have a tremendous affection for software that does one thing and does it really well. Due, from developer Lin Junjie, is like that. It’s about the reminder, the simple nudge in the ribs to draw your attention to a task that may be need to be done as infrequently as once, versus the “task” or the “project,” ungainlier creatures that can have multiple steps and deadlines. It’s uncomplicated, beautiful and functional. My only beef with it is that it includes a secondary functionality that’s sort of neat, I guess — you can define and save timers of varying lengths keyed to different events — but which I never use. Just knowing the timers are there detracts a tiny bit from the gorgeous simplicity of the thing. I’m a purist that way. But is Due in every other respect an essential addition to my home screen? Absolutely. It passes the highest test I can imagine for an iPhone app: It’s so smart, and so pretty, I can’t imagine why Apple didn’t bake something like it right in.