NUnit is a unit-testing framework for all .Net languages.

Cloud test automation framework that enables businesses to maximize their test automation across the complete testing process from an End User´s perspective.

FlaUI enables reliable end‑to‑end UI automation for Windows applications, offering a clean .NET interface over Microsoft’s UI Automation APIs (UIA2/UIA3) to test Win32, WinForms, WPF, and UWP apps.

HyperTest is a no-code test automation tool that regresses all your APIs by auto-generating integration tests using your network traffic, also giving a way to reproduce these failures inside actual user-journeys.

Test, scrape, generate, and automate without the pain and expense of hosting your own headless browsers.

Robot Framework is a generic open source automation framework. It can be used for test automation and robotic process automation (RPA).