Over the last 10 years, I've been maintaining several .NET open-source projects, of which one, Fluent Assertions, has crossed the 90 million NuGet downloads. This may sound like a trivial thing, but I can tell you first hand that maintaining a successful open-source project requires patience, perseverance and a lot of time. I.o.w. the exact same challenges that you face in your real-life day job, especially if you've been trying to break down your monolith into smaller components, libraries and services maintained by various folks. I'll start with a bit of history about this project to help you understand how similar it is to real project. Then I'll dive into the characteristics of a great library or component, .NET framework compatibility, the branching and release strategy, and the build pipeline. But I'll also cover some aspects of (internal) marketing, dealing with cross-team contribution, documentation and support aspects. I'll wrap up with design guidelines that I now apply on all my internal projects.