Earlier this month, Flipt, a Seattle-based startup, launched with a big goal. The site was hoping to take down the web’s biggest real estate sites by offering “more than simple home listings.”

The site boasted “a complex algorithm, featuring machine-learning capabilities to interpret a mixture of publicly available and propriety data to determine how a consumer can best profit from a specific property.”

A visitor to the site could search to see available properties in their desired zip code. The properties were ranked on a 0-100 scale in three categories, “Fix & Flip”, “Buy & Hold” or “Rent Out.”

The intention of the rankings was to provide insight into the viability of the property in those three categories to “match consumers with properties based on their unique desired outcome.”

Below is what the site's search results page looked like. 

Flipt screenshot

But if you visit the site today, you won’t see a search option or a list of properties. Instead, you’ll see this message: “We will be back. Thank you for your support. We have experienced an overwhelming amount of demand. We are working hard to improve our service. Sign up to receive an update when we relaunch.”

That’s because the site was allegedly using proprietary data from Zillow (Z) to fill in its real estate listings, according to a report from Geekwire. Zillow sent a cease-and-desist letter to Flipt alleging that the startup was violating Zillow's terms of use.

“Zillow regularly takes steps to protect our intellectual property rights, and the manner in which Flipt was using Zillow data was in clear violation of our terms of use and other protections we operate under and we instructed them to stop immediately,” Zillow said in a statement issued to GeekWire.

Flipt’s CEO Andrey Nokhrin told GeekWire that he was surprised to receive Zillow’s letter but removed all of Zillow’s data from the site post haste.

According to GeekWire, “Nokhrin said the company was having trouble obtaining real estate data, so he said they came up with a ‘quick hack’ so that they could validate demand for the Flipt service. He said the methods they used are the same that ‘Bing does to index sites.’”

But it appears that Flipt’s “quick hack” ran afoul of Zillow’s terms of use and Zillow responded in kind. Now, Nokhrin says the site is “pivoting to focus on services for real estate professionals.”

So the lesson here is clear. If you take on the big boys, it’s probably not a good idea to “hack” them for their data. Or In other words, paraphrasing the immortal Principal John Bender from “The Breakfast Club,” if you mess with the bull, don’t be surprised when you get the horns.