Rack::Cargo - Rack middleware to handle multiple API requests without multiple HTTP round-trips. Useful when you want to get, say, a customer and all their orders but they use two separate endpoints.
Git Cop - Want to enforce styling and conventions on your team's git commits? Here's the tool.
Katacoda - "Interactive Technical Learning Platform for Software Engineers" with a wide variety of courses on topics like Docker, Kubernetes, git, Terraform, Tensorflow and plenty more.