Glad you like it. I've also been looking for such a solution for years, and except for the short-lived Flock by the Open Whisper Systems people, I couldn't fin

Glad you like it. I've also been looking for such a solution for years, and except for the short-lived Flock by the Open Whisper Systems people, I couldn't find anything. That's why I finally decided to create it almost a year ago. Edit: you just edited your reply while I was writing mine, to answer your additional question: For a variety of reasons, the browser is not a safe environment for such an application, at least not currently. There is however a CalDAV/CardDAV gateway (beta) that you can host locally and essentially use any application that supports those to quickly edit your data, or alternatively, if you are a programmer, there's an open source (like everything from EteSync) python API (both low-level and high-level) that you can use to manipulate the data.