Personally I use Google Keep. The reason I like it is because I can use it to write notes, set alarm on notes, I can create shopping lists with it, and if I want to get creative, even to-do lists, although the latter is better done with Google Tasks. And, for me, best of all, it’s synced across all of my devices, computer, phone, tablet. The bad news is, Google Keep does not have an API, however Google Tasks does, it’s a REST API.
I’ve thought about it quite a bit actually, but haven’t had time to actually start looking at what it would take.