You're using Reddit to self-promote your app. Even in subs where doing this doesn't get you banned, lots of readers will downvote this behavior anyway.
On top of that, it appears the app offers pretty trivial functionally of dubious utility, so maybe it's not some conspiracy against you, maybe people just don't find it very interesting.
Finally, I'm struggling to imagine what posting your complaint on HN could accomplish...
https://old.reddit.com/report under "Vote manipulation".