I think that Zillow would shut that down ASAP. I'd review the terms of service to see what's allowed.
OP, I don't know your background, but if you are serious about real estate tech, I'd recommend getting your real estate agent's license and buy/sell a few homes. That'll give you an appreciation for:
* the sheer amount of money that flows through the system
* the non-fungible (and variable, over time and per person) nature of homes
* the stakeholders
* the amount of technology already in use
Or you could go work for a real estate tech company (like Zillow, OpenDoor, Boomtown, or any of the MLSes) and gain some expertise that way.