Artsy

Eigen is actively maintained with a 'State: Production' status and established CI/CD via CircleCI, providing a real-world example of deployment processes.

Artsy's 'Open Source by Default' philosophy means full access to development practices, as noted in the README's links to engineering principles and blogs.

The README includes detailed guides for setup, best practices, and deployment (e.g., deploying to beta and App Store), easing onboarding.

With designated point people and regular CI checks, the project is reliably updated, as highlighted in the 'Meta' section with contributors and status.