Looking for a software that helps to keep track of the client's spec.

Have you ever found yourself struggling to keep track of all the changes that your client requests in their project specifications? Whether it's for a website or an app, clients often have last-minute changes or updates that can quickly become difficult to manage and grow into new features that should be billed as extra. Do you know of any such software that can keep track of changes, updates, questions, and progress in one place? I am looking for one, it should preferably be available for the client as well so that he or she can log the requested changes. I am currently using emails and google docs and it is a hassle. I would appreciate any suggestions!