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

SelectorsHub is the Next Gen XPath Plugin & Selectors tool. It supports all kinds of XPath, locators, shadow dom, iframe, svg, dynamic elements, multi selectors generation and xpath error handling. It is a Free community product.

Appium is an open-source project and ecosystem of related software, designed to facilitate UI automation of many app platforms

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.

Webomates provides cloud-based Testing as a service (TaaS) to leading software companies

Codeless automation tool. Allows anyone and everyone to automate with ease. Not just record and playback!