Best SaaS for a Consultant?

A search actually does not result in anything meaningful on this. A family member who does business consulting is looking for a software solution to track multiple clients who they help. Not time based at all (no need to track time) just flat rate projects for work they do. Just one person firm (not multiple people) and no need to interface with the clients on the system (although I guess if that was a feature would be nice).

So far all I was able to turn up was Atlassian offerings but interested in ways people typically do this or what else is out there. The person is not a computer or software consultant but what they do is close enough that a solution that works for that would work here.

Once again did do a search but all I get are 'SAAS Consultants'...