deal-lens

DealView (Beta)

The “Bullshit Detector” for Zillow. Stop guessing and start underwriting like a pro—directly on the listing page.

Why DealView?

Zillow’s “Estimated Monthly Payment” is designed for homeowners, not investors. It misses the variables that kill cash flow: closing costs, repair budgets, and the inevitable 2026 property tax reassessment. DealView bridges the gap between a Zillow listing and a professional spreadsheet.

Key Features

Search Results — Gross Yield Badge

Every listing card gets a gross yield badge before you click in. Gross yield is annual rent ÷ list price — the fastest way to filter deals at a glance.

Green (≥ 6%) — Passes the rough 1% rule. Worth opening the analyzer.
Amber (4–6%) — Marginal. Market-dependent, worth a look.
Red (< 4%) — Unlikely to cash flow in most markets.

Rent data comes directly from Zillow’s own Rent Zestimate — no external API, no cost, no guessing. Listings with no rent data (new construction, etc.) show no badge.

Listing Detail — Full Investor Analysis

Lender-Ready DSCR: Instantly see if a property qualifies for a 1.25+ DSCR investment loan.
True Cash-on-Cash (CoC): Accounts for down payment, closing costs, and your estimated repair budget.
Tax Reassessment Warning: Built-in alerts for the “Year 2 Tax Jump” common in most states.
Live Rent Override: Stress-test any deal by adjusting the rent estimate — see DSCR update in real time.
Persistent Inputs: Your closing costs, down payment, and interest rate are saved locally; no re-typing required.
Reset Inputs: One click restores all analysis inputs to defaults.
Side-by-Side Comparison: Save up to 10 properties and see “Best Performer” badges for CoC, DSCR, and GRM instantly.

Privacy & Security

No Accounts: Use it immediately. No email, no password, no friction.
No Servers: All property data and your saved list live in chrome.storage.local. We never see your data.
Minimal Permissions: Only zillow.com access and local storage. No tracking across other sites.

How to Use

Install: (Chrome Web Store link coming soon)
Open Zillow: Navigate to any search results page — yield badges appear automatically on every card.
Click a listing: The DealView panel loads automatically with the full investor breakdown.
Adjust Your Inputs: Edit the rent estimate, toggle 30yr/15yr/custom rate, or add a repair budget.
Read the DSCR First: If it’s red, a bank likely won’t finance it — regardless of how the CoC looks.
Save & Rank: Click “Save Analysis” to compare your top deals in the list view.

Metrics Explained

Metric	What it means
Gross Yield	Annual rent ÷ purchase price. The quick-scan filter. ≥ 6% passes the 1% rule.
Cap Rate	Annual NOI ÷ purchase price. Financing-independent return. 5%+ is solid for residential.
Cash-on-Cash	Annual cashflow ÷ total cash invested (down + closing costs + repairs). Your real return.
DSCR	NOI ÷ annual mortgage. Lenders require ≥ 1.25 for investment loans.
Monthly NOI	Rent minus operating expenses (excl. mortgage).
GRM	Price ÷ annual rent. Under 15× is strong; over 25× is expensive for cash-flow investors.

Expense ratio default: 40% of gross rent — split into property management (7%), vacancy (5%), and taxes/insurance/maintenance (28%). All three are editable in the panel.

Data Sources

Every number in the panel traces back to one of these sources:

Data	Source	Cache
List price, beds/baths/sqft, status, address	Zillow DOM (`data-testid` selectors)	Live
Rent Zestimate	Zillow `__NEXT_DATA__` SSR blob (hard load) or DOM element (SPA nav)	Live
Mortgage rate (30yr / 15yr)	FRED API — series `MORTGAGE30US` / `MORTGAGE15US`	24 hours
HUD Fair Market Rent	HUD API — SAFMR zip-level, falls back to county average	30 days
Census median rent + household income	Census ACS 5-year estimates (2023), variables `B25064_001E` + `B19013_001E`	90 days
Annual property tax	Zillow Facts & Features module (DOM regex on `data-testid="facts-and-features-module"`)	Live

ZIP code and state are extracted from the listing address h1, with a fallback to the Zillow URL path (e.g. /homedetails/123-Main-St-Austin-TX-78749/...) for reliability when the DOM is slow to render.

Calculations

Mortgage Payment (P&I only)

Standard amortizing loan formula:

M = P × [r(1+r)^n] / [(1+r)^n − 1]

P = listPrice × (1 − downPaymentPct)   (loan amount)
r = annualRate / 12                     (monthly rate)
n = termMonths                          (360 for 30yr, 180 for 15yr)

Example: $500K home, 20% down, 6.85% rate, 30yr → $2,626/mo

Operating Expenses

totalExpenseRatio = pmFeePct + vacancyRatePct + otherExpenseRatio

monthlyExpenses = rentEstimate × totalExpenseRatio

Defaults: 7% (PM) + 5% (vacancy) + 28% (taxes/ins/maint) = 40% total

When Zillow provides the actual annual property tax, the taxes/ins/maint field pre-fills as:

adjustedOther = min(round(annualTax / 12 / rent × 100) + 13, 45)

The 13% is a fixed allowance for insurance + maintenance. The actual tax % replaces the estimated tax within the 28% default.

Gross Yield

grossYield = (rentEstimate × 12) / listPrice

The “1% rule” in yield terms: monthly rent ≥ 1% of price → 12% gross yield.

Net Operating Income (NOI)

monthlyNOI = rentEstimate × (1 − totalExpenseRatio)
annualNOI  = monthlyNOI × 12

NOI is independent of financing — it measures the asset’s income as a business.

Cap Rate

capRate = annualNOI / listPrice

The return assuming all-cash purchase. Lets you compare properties independent of how each is financed.

Monthly Cashflow

monthlyCashflow = rentEstimate − monthlyMortgage − (rentEstimate × totalExpenseRatio)
               = monthlyNOI − monthlyMortgage

Negative = net out-of-pocket cost every month.

Cash-on-Cash Return

totalInitialInvestment = (listPrice × downPaymentPct) + (listPrice × closingCostPct) + repairBudget

cashOnCash = (monthlyCashflow × 12) / totalInitialInvestment

Your actual return on every dollar brought to closing — accounts for leverage, all expenses, and real out-of-pocket cost.

DSCR

dscr = annualNOI / (monthlyMortgage × 12)

≥ 1.25 — lender-ready for DSCR investment loans (green)
1.0–1.25 — NOI covers mortgage, but below lender threshold (amber)
< 1.0 — NOI does not cover the mortgage payment (red)

Min rent for 1.25× DSCR (shown when DSCR < 1.25):

minRent = ceil((1.25 × monthlyMortgage) / (1 − totalExpenseRatio))

Derived by solving (rent × (1−expenses) × 12) / (mortgage × 12) = 1.25 for rent.

GRM (Gross Rent Multiplier)

GRM = listPrice / (rentEstimate × 12)

Inverse of gross yield × 100. Under 15× is strong; over 25× is expensive for cash-flow investors.

Rent-to-Income Ratio

rentToIncome = (rentEstimate × 12) / censusMedianHouseholdIncome

Measures tenant affordability in the ZIP. Above 30% = housing burden threshold, higher vacancy risk. Source: Census ACS B19013_001E.

HUD Fair Market Rent

U.S. Dept. of Housing and Urban Development publishes FMRs annually. Represents the 40th percentile of gross rents — what HUD will pay for Section 8 housing. A government-set floor: the lowest the market is expected to sustain. Good conservative underwriting baseline.

Tier shown in the panel matches the listing’s actual bed count (efficiency / 1BR / 2BR / 3BR / 4BR+).

Development

cd extension
npm install
npx wxt dev     # builds + watches for changes

Built with WXT · React · TypeScript · Chrome MV3

Disclaimer

DealView is an estimation tool. Real estate investing involves significant risk. Always verify your final numbers with a licensed lender and local tax assessor.

Feedback & Bugs

Found a bug? Zillow changed their layout? Email caleb@mazowventures.com or open an Issue on this repo.