It's one of those things that annoy me about reading an open source project describe themselves: you can be four paragraphs in and still don't know what it does.
Of course the license and stuff are also important, but why does it need to be your opening sentence?
Things that are not «features» of an app:
- The license
- The technologies it uses
- The fact that it’s simple
- The application it’s an alternative to
Your app should be compelling on its own. What makes it worth using? How can it help people? Highlight those things instead!
