Impressive.
Do you mind sharing the technologies you are using?
Let me think here for a moment:
If I were to build a service like that, first thing to think about is the connectors, are there open source database connectors?, I guess maybe at this point there is a lot of them. But then you have a lot of other parts to do. The SQL cells (as you call them), how everything talks to one another, the charts, the tables, the comments. Well done, man.
I have two more questions: did you have an experience working on something similar before? and what is the chart lib are you using?
I completely understand if you don't like to share these info.