TestRail’s web-based test case management is used by thousands of great QA and Development teams to efficiently organize, track and manage software testing.
Postwoman - An online, open source API request builder
PractiTest - PractiTest is a cloud based Innovative test management tool.
Postman - The Collaboration Platform for API Development
Sauce Labs - Test mobile or web apps instantly across 700+ browser/OS/device platform combinations - without infrastructure setup.
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.
TestLink - Test & requirements management