I have been a Fusebase (formerly Nimbus) user since 2020, and it is the software I use most out of all my purchases from AppSumo. I use it internally in the office, with clients, and even my daughter uses it to organize her university resources. What I like most is that it seems like a system without limits. I'm sure I only use 50% of its capabilities, and they keep adding new features. That's another strong point, which has improved a lot in 5 years. I bought a Tier 1 now, without thinking too much about it, so I can access the new features. For me, it's a must-have.