Inspiration
Starting January 7, 2027, the ROAD to Housing Act says no one who owns 350 or more single-family homes can buy another. The catch is that big landlords don't buy under their own names. They use hundreds of LLCs with names like ALTO ASSET CO 7, and each one looks like a small landlord. Nobody enforcing the law could actually see who's over the line.
## What it does
Plainsight traces 1.07 million company-owned homes in six states back to the companies that own them. It found 94 owners already past 350 homes. You can look up any address or LLC, check a buyer before a closing, follow new purchases, and download the evidence for any owner. It also matches city housing-code violations to owners, so you can see which landlords actually let their homes fall apart.
## How we built it
We pulled public parcel records from each state and linked LLCs using shared mailing suites, numbered names, sellers, neighborhoods and buying patterns. SEC filings gave us known subsidiaries to train on and named the companies behind several anonymous owners. We also fine-tuned a small model on the hardest cases. The app is React and MapLibre on a Python and DuckDB backend, hosted on Vercel.
## Challenges we ran into
LLCs are easy to disguise. Rename one and move its mailbox and simple matching misses it, so we built a test set full of disguised LLCs to make sure we didn't. Fitting a million homes onto Vercel's free hosting took a lot of squeezing too.
## Accomplishments that we're proud of
Invitation Homes reports its home counts to the SEC. Working only from deeds, we found 100% of its homes in Florida andPhoenix.
## What we learned
What an LLC does says more than what it's called. A company can rename everything, but it still buys in the same neighborhoods from the same sellers.
## What's next for Plainsight
More states, daily alerts on watched owners, and violation data from more cities.
