Now live in the Chrome Web Store

Underwrite Zillow deals in 5 seconds.

A free Chrome extension that adds A/B/C deal grades, live cash flow, cap rate, and cash-on-cash to every Zillow listing — so you stop wasting time on bad deals.

Add to Chrome — Free ⭐ Free forever · No login · No data collection
zillow.com/homedetails/123-Main-St-Philadelphia-PA
123 Main St, Philadelphia, PA 19146
3 bd · 2 ba · 1,420 sqft · Built 1925
Deal Grade
A
+$343/mo
Cap rate7.8%
Cash-on-cash9.2%
1% rule✓ Passes
Est. monthly rent$2,150
PITI$1,807

Built by an investor, for investors.

Stop opening 30 Zillow tabs and copying numbers into a spreadsheet. Every metric you actually care about, on the listing, automatically.

A

A/B/C deal grades

Every listing and search-result card gets a grade based on cash flow and cap rate, so the bad ones are obvious at a glance.

$

Real PITI cash flow

Full principal, interest, taxes, insurance — plus vacancy, capex, and maintenance reserves. The math you'd do, but instant.

%

Cap rate & cash-on-cash

Two metrics that actually matter for rentals. Updated live as you adjust your down payment or expenses.

📍

ZIP-level rent estimates

Powered by Zillow's public ZORI rent dataset — ~30,000 ZIPs covered, refreshed monthly. Override per-listing if you know better.

📈

Live mortgage rates

30-year fixed pulled from Freddie Mac (FRED) weekly. Or override manually if you've got a better quote.

🔒

100% private

No login, no analytics, no telemetry. All math runs on your device. We literally cannot see your data.

🎯

Filter search results by tier

One click hides every C-tier deal on a Zillow search page. Only see the A's and B's worth your time.

⚠️

Plain-English risk callouts

"Negative cash flow at 25% down" or "Rent estimate is below ZORI median" — flagged automatically.

🏠

Equity build & true return

Includes principal paydown in your year-one return — most calculators ignore this, you shouldn't.

Get started in 30 seconds.

No signup, no payment, no learning curve.

Add to Chrome

Click the button below. Chrome handles the install in one click — no password, no account.

Open any Zillow listing

The deal panel appears on the right side of the page automatically. Search results get colored A/B/C badges.

Tune your assumptions (optional)

Adjust down payment %, vacancy, capex, or the mortgage rate. The numbers update instantly.

Add to Chrome — Free
Developer / unpacked install (advanced)

If you'd rather load the extension from source instead of the Chrome Web Store:

1. Download zillow-deal-analyzer.zip · 2. Unzip it · 3. Visit chrome://extensions and enable Developer mode · 4. Click Load unpacked and select the unzipped folder.

Firefox users: Firefox build · load via about:debugging#/runtime/this-firefox.

FAQ

If you're a real estate investor, you've probably wondered all of these.

Is this affiliated with Zillow?

No. Zillow® is a registered trademark of Zillow Group, Inc. This extension is an independent third-party tool that analyzes publicly visible Zillow listings on behalf of the user. It is not affiliated with, endorsed by, or sponsored by Zillow Group, Inc. in any way.

How accurate are the rent estimates?

Rents come from Zillow's public ZORI (Zillow Observed Rent Index) ZIP-level dataset — actual market rents observed across roughly 30,000 ZIP codes, updated monthly. They're scaled by bedroom count using HUD's standard multipliers. For markets without ZORI coverage, we fall back to HUD Fair Market Rent baselines. You can override per-listing if you know your local market better than the data does.

What data does the extension collect about me?

Nothing. No account, no analytics, no telemetry. The extension reads only the Zillow listing you're currently viewing and computes everything on your device. The only network requests it makes are to fred.stlouisfed.org (mortgage rate, weekly) and files.zillowstatic.com (rent dataset, quarterly). See the privacy policy for the full breakdown.

How is this free?

The extension is fully free. The maintainer earns small affiliate commissions from a few opt-in tools (like Stessa for property tracking) when users sign up through links in the panel. Affiliate placements are clearly labeled and never influence the deal math.

Where do the mortgage rates come from?

The 30-year fixed rate is pulled from Freddie Mac's Primary Mortgage Market Survey (PMMS) via the FRED public API, refreshed weekly. You can override it manually if you've locked a different rate with your lender.

Does it work on Safari, Firefox, or Edge?

Live on Chrome today. Edge support is coming (the same build works — pending submission). Firefox build is available as a developer install in the section above. Safari support requires Apple Developer Program membership and is being evaluated based on demand.

Can I use this for multifamily / 4+ unit properties?

Today the extension is calibrated for single-family and 1-3 unit small-multi rentals — that's where Zillow's data and ZORI rent estimates are most reliable. Larger multifamily support is on the roadmap.

Is this financial advice?

No. The deal grades and cash flow numbers are estimates based on public data and your inputs. They're a starting point for your own due diligence, not a recommendation to buy. Always verify rents, taxes, insurance, and condition with local sources before committing capital.

Stop guessing. Start grading.

Free forever. 30-second install. No signup.

Add to Chrome — Free