I tried out a few from this list of rv apps and like one of the other posters I think camp and RV from all stay is probably the best though as mentioned before I dont know that there is a complete database.
I really like All Stays and it's much more than just CGs. Want rest stops, RV service, Walmart, CP, NP, low bridges and many other options. Plus hundreds of CG options like 50A, etc.
You select the options you want and you're not wading through tons of unrelated text.
Works great on the iPhone where you have mobility unlike laptop portability. Right now I'm at a CG that is 1+ years from membership only transition and did not show up anywhere else and certainly not in outdated guides like Trailer Life, etc.
2009 Holiday Rambler 42 Scepter with ISL 400 Cummins
750 Watts Solar MPPT 60 Controller
2004 Honda CR-V