Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.

TestRail - TestRail provides comprehensive test case management for software testing. Organize your testing, boost productivity, get real-time insights, and track progress toward milestones. Integrates with leading issue tracking and test automation tools.

Ranorex - Ranorex is a GUI test automation framework for testing of desktop, web-based and mobile applications.

TestLink - Test & requirements management

Cucumber - Cucumber is a BDD tool for specification of application features and user scenarios in plain text.

Klaros-Testmanagement - Klaros-Testmanagement is a professional web based test management tool.