Currently it's still a side project (started a few days). My plan included the following phases:
1. Idea + POC (solved technical issues) => Done
2. Build a MVP => Done
3. Get some feedback and see if there is any interest. => Here we are!
4. Based on feedback, add (premium) features but keep the basic service for free.
So in summary; yes it will stay free, I might add some "acceptable" limitations but the goal is indeed to propose additional (non-free) features like well-known services (for instance Gitlab).So feel free to share your ideas, I would enjoy to answer and challenge them!
Furthermore I plan to write a small survey to get more feedback.
About the "Open Source" part: as a regular FOSS contributor, I do not exclude to publish sources. However, publishing sources means maintaining them. And I don't want to maintain a useless project. So currently I don't want to publish them.
Hope it helps you to understand my strategy for this new experience!
This one is neat because the author chose to restrict to the qr code "alphanumeric" character set that includes a couple symbols to reduce bits per character in the encoding. Now that you're aware of that, you could certainly do that yourself or modify another shortener to do it.