I launched Duet (http://duetapp.com) in May 2013 and it's been profitable since day 1. I'm going to start focusing on it more so it can hopefully grow into something I can live off of.
*edit: I'm very curious to know, what about this comment is worthy of downvotes.
i would guess it's the difference between "making revenue since day 1" and "profitable since day 1".
it's hard to imagine that you recouped all of your time/money/expenses not to mention that going forward, you can work on it full time -- all as of day one.
Beautiful app! I love the UI. Is this a single-person project? How long did you develop before release? Is the front-end just jQuery and Foundation (no larger JS framework)?
Yes, it's a single person project. The initial release took a long time; I was working on it between freelance projects. I'm using a custom jQuery MVC implementation on the front end, some twitter bootstrap, and a couple of 3rd party plugins (i.e. ckeditor, nanoscroller, pdfjs, etc)
It's just me - one person. I'm still figuring out marketing. It's difficult. I wrote about some of the marketing challenges I've had on the blog http://duetapp.com/blog
*edit: I'm very curious to know, what about this comment is worthy of downvotes.