Microsoft is developing dotnetup (netup), a new cross-platform .NET SDK and runtime version manager designed to unify the fragmented landscape of .NET installation methods. Unlike existing approaches (Visual Studio, Homebrew, package managers, install scripts, DNVM), netup provides user-level (no elevation required) installs that work consistently across Windows, macOS, and Linux. Key features include: reading global.json to auto-install the correct SDK version, installing individual runtimes without full SDK downloads (enabling multi-runtime testing with a single SDK), tracking installed components in a manifest for auditable updates, and automatic cleanup of outdated installations. Built with native AOT for speed, it targets both human developers and CI/CD agents. The roadmap includes self-updating, signature verification for supply chain security, oneshot execution for A/B testing SDK versions, agent skills for LLM integration, and eventual CI/CD action integration. Currently in internal preview, public preview is targeted before end of summer.