For the last couple of month I've been developing this little application that allows you to do many things to grow you audience on twitter even without opening twitter application itself! I would be glad for any feedback and idea validation :D
You can check out the latest version of the landing page here https://tweetastic-v2.netlify.app/ - I've tried to make it self explanatory and reinforced it with real screenshots from the web app.
So far Tweetastic allows:
Tweetastic has entered public beta and it's totally free to use by everybody until there is a stable version with payment plans.