"I built a version control system, in my free-time, called Jam" is fine.

Just "I built a version control system called Jam". The free-time thing is good for a history page but the homepage needs to tell the important part (you've got history and expertise in this subject) and then move onto what the vision is for Oak and what kind of help you need.

It's also fine without the commas, because nobody was confused by that structure.