Zactly was built as a solo hobby project that I intended to use personally when carrying out design or research in my day-to-day work. Having enjoyed the project so much, and after getting some positive feedback from colleagues, I may make it public in future.
Zactly is a design tool for product and service designers. It allows you to keep track of all the assumptions you have made about your product, its functionality, who its users are and how it will be used.
When you track all of the assumptions made during the design process, it becomes easier to plan and execute research needed to validate these assumptions, even if it's been months since the assumption was made.