What is the coolest open source project you've seen in the past year?

Godot game engine, definitely. Sure, it still have a long way to go, but it is getting quality updates regularly that the hype for the updates is mind blowing. I can definitely see it being a serious rival to Unity in a few years, at least in the 2D market.

For me, I am most excited about MLFlow. Having worked in this space for awhile, good MLOps is a wonderful thing!

But I am always curious what else people are doing to save the world or, at minimum, make life better/cooler/smarter.

For me it's Kubernetes. It's just amazing.