I'm releasing the code for an Instagram hashtag finding application that I spent a few months building. I no longer have any use for it because I have completely quit using Instagram.
If you know how to navigate through a rails codebase, this should be fairly straight-forward. I'm pretty sure that to get going, all you need to do is add your IG API keys to config/initializers/constants.rb and then:
bundle installrails s
You'll also need to be running a redis-server instance as well as Sidekiq for the background processing.
If you want email, you'll need to add your credentials to config/sendgrid.yml.example and rename that to config/sendgrid.yml
Do what you want with this, commercially or otherwise.
You're free to use this code but I'd recommend against using it in production with Instagram. You'll just be setting yourself for a constant uphill battle against a company that does not give a single fuck.