You should try Reddit. It has a lot of niche communities where you could share your project.
Also Google for things someone who seeks for a project like yours would Google. That gives you a rough idea of what kind of sources people use to find tools like yours.
Also some directories list specific tools (like "awesome" lists of github). Try listing your project there. Or even starting your own "awesome" list project on GitHub :)
There are other subreddits too which are trying to find cool projects like yours.
Other approach is to write a blog post and post that to e.g. /r/opensource