It's worth mentioning that we don't just talk externally about Open Source. Internally, the Mobile team runs talks about Open Source for the rest of the Artsy staff. As well, we discuss the tooling and business implications of having our work in public repos. Artsy strives for an open culture, in this case the development team, on the whole, is just further along in the process.
The Open Source app idea started with an experiment in the Summer of 2014, asking, "What does a truly Open Source App look like?" The outcome of that was our Swift Kiosk app, Eidolon. Open from day one. We took the knowledge from that and applied it to our public facing app, Eigen. Open from day 806. That made 2/3rds of our apps Open Source.
I'm going to talk about our final app, Energy. Open from day 1433 and ~3500 commits.
Energy is commonly known as Artsy Folio. It's a tool for Artsy's Partners to showcase their artworks on the go, and quickly email them. Here's a beautiful splash showing it in action.