I have subscribed to two subreddits that sort of cover this. The first is /r/SideProject. It is a place that people post their side projects and occasionally blogs/articles about their side project. The pros of it is that people don't frown on self promotion but the con is that there doesn't seem to be many comments going on to help improve your offering. The second is /r/lookatmyprogram although that sub seems to be dead. The bigger (if not the biggest) software subreddit is /r/programming but they state that "App demos should include code and/or architecture discussion." so you wouldn't be able to flat out promote.
> but they state that "App demos should include code and/or architecture discussion." so you wouldn't be able to flat out promote.
Unless architecture/code is a selling point, of course.
Also, /r/software and some of its ilk might be a good place to look at, though I don't know about promotion (it seems to be the other way around: people looking for software that does a particular task).
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