There are many open source testing tools that help you to arrange test cases, create documents, specify tests, and run those tests.These tools provides a structured approach to software testing and increases the visibility of the testing process by creating a common repository for all test assets including requirements, test cases, test plans, and test results. Here are some of those:
Testopia
Fitnesse
qaManager
Radi
Tarantula
XStudio
TestMP
Litmus
I hope you might get one as per your needs.
I would suggest using cloud-based spreadsheets such as Google sheets for managing your test suite, since these are open source tools. They afford all the benefits of a cloud service such as shared access among the team members, and access control (you can control who gets access to which sheet), and ease of updation. For each test case, you can attach notes, see the revision history and you can even insert video links so that bugs can be easily reproduced. I am a technical writer for OnPath Testing and I have written this article on 'Managing regression using spreadsheets', which explains how managing your test suite using spreadsheets is easy and helps maintain clarity in the testing process.
StickyMinds is a TechWell community.
Through conferences, training, consulting, and online resources, TechWell helps you develop and deliver great software every day.