I am interested in the general rules/regulations of having an opt-in style site/web-based app, where users (agents/brokers) can submit their IDX/RETS data for inclusion within the app that aggregates and displays this data in a variety of ways.

The app would acquire/parse that data -> copy it locally, create crons, etc.

From what I've been reading about MLS data, is that its NOT publicly available information and as such is not accessible to a web developer as myself, BUT agents are allowed to manually add listings to other third parties if they so choose (Trulia, etc).

I might not fully understand the mechanics of integrating an app with the IDX/RETS data feeds, so maybe this isn't even technically possible. I'm currently in brainstorming mode, and need to know if its worth my while to keep moving forward.

Can someone point in the right direction in terms of rules/regulations with this regard?

*Side Note* I am not immediately interested in making any gains from such an app if it means skirting the rules/regulations, but rather it more akin to the way craigslist operates.

Let me know if anything is unclear. I'll do my best to clarify. Thanks!