Hi, I and my friend Furkan have developed a simple product for Slack. As you may know, auto invitations for the free version of Slack is a problem. I needed a basic widget and a landing page for my slack channel so I come up with this solution Community Inviter.
With CI, you can easily set up an invitation widget and a landing page to get invitations for your slack channel. You can either approve them manually or automatically. All of those features are free. You can also ask questions to applicants in the landing page. This is the part we charge $5/month.
We are in public beta right now, and appreciate all of your feedbacks.
Community Inviter