Steemd development

I signed up for Steem a while ago and never really used it. I have some ideas about developing an app with a steemd backend so i am getting more involved now.

So i guess all the data stored in the blockchain is available to everyone using steemd as their datasource... I'm looking at docs now. Basically seems like we are all frontend developers. I would like to be able to limit my site/app to only display posts created from my site. Any guidance would be appreciated.