UNDRLY
Get Undrly
Chrome extension · Zillow & Realtor.com

Instant deal analysis for beginner and intermediate rental investors.

Undrly is a Chrome extension that runs full rental underwriting on every Zillow and Realtor.com listing as you browse - cash flow, cap rate, break-even, the seller's position, and an honest verdict, rendered right on the page. Long-term analysis is free; short-term mode with live Airbnb market data is Pro.

Get Undrly - free See how it works →
UNDRLY
Monthly Cash Flow
+$179/mo
SOLID
List Price
$
6.0/10
Deal score · Better than 21% of the 14 LTR properties you've viewed Reset history
Price
Listing
Sqft · Beds
Listing
HOA
Listing
Rate 6.55%
FRED · Live
Last sale
Price history
Tax
Reassessed est.
Insurance
Rebuild est.
SummaryFlags 3MathAssumptionsResources
Cap Rate
4.6%
Cash-on-Cash
−4.9%
Monthly PITI
$2,871
Break-even Rent
$3,302
Cash to Close
$124,120
Price / Sqft
$226
1% rule: 0.65%Rent basis: median of 8 nearby 3-bed comps
Owned9.4 years · bought Mar 2017
They paid$210,000
Your $429,000 price vs. their purchase+$219,000 (+104%)
Est. equity at this price≈ $268,000–$296,000
Est. walk-away cash≈ $238,000–$266,000
Negotiation read
Deep equity — room to move. Your offer costs them profit, not a check at closing. Assumes no refinance — not visible in listing data.
Down payment 25% Rent$
What this could rent for
Live Market PRO25 comps · AirROI
$248 at 62% booked · $4,674/mo gross
Occupancy62%
Pricing and revenue
Avg nightly
$248+7%
ADR range
$180–342
RevPAR
$154
Annual rev
$56.1k
Demand and occupancy
Occupancy
62%+4
Adjusted
55%
Booked
227/365
Avg stay
3.2 nt
Market and competition
Superhost
38%
Min stay
2 nt
Pro-managed
44%
Cleaning fee
$145
Guest experience
Comp rating
4.87
Reviews
96 avg
Guest favorite
31%
Capacity
8 guests
9 of 50 lookups used this month · resets in 21 days
LTR mode: 5% vacancy, 8% maintenance reserve, tax reassessed at your purchase price, live 6.55% 30-yr rate. · Disclaimer · Report an issue
live demo — the exact panel, running its real math on a sample Largo, FL listing (3 bd · 2 ba · 1,480 sqft). Edit anything.
Getting started

Up and running in under a minute.

One install, zero setup. By the time you've looked at the photos, the underwriting is already on the page. New to investing? Read the full walkthrough - every number explained in plain English.

+ Add to Chrome
1
Add it to Chrome
One click from the Web Store. No account, no signup, no card - long-term analysis is free forever.
Panel appears ✓
2
Open any listing
Browse Zillow or Realtor.com like you already do - the panel builds itself from that listing's real numbers.
SOLID
3
Read the verdict
Cash flow, cap rate, break-even, the seller's position, and flags from the description - with a verdict honest enough to say PASS.
Who it's for

Built for the way you actually shop.

Whether it's your first deal or your fortieth, the panel meets you at the same place - the listing you're already reading.

First deal
Buying your first rental
The guardrails matter most on deal one: reassessed taxes instead of the seller's bill, Airbnb's real fees instead of the 3% myth, and a verdict honest enough to say PASS before you overpay.
Growing
Scaling a small portfolio
Screen thirty listings in the time a spreadsheet handles three. Save the contenders, rank them by score or cash flow, and only open the spreadsheet for the ones that survive.
Time-strapped
Experienced, short on time
A fast snapshot you can actually trust - every number labeled with its source, every estimate labeled as one - so you know in seconds whether a listing deserves real diligence hours.
How it works

Five tabs. Every number you need.

Install it once. Undrly quietly attaches to Zillow and Realtor.com and runs the full analysis - Summary, Flags, Math, Assumptions, and Resources - the moment a listing loads.

Works right on the listing
No copy-pasting into a spreadsheet. The analysis panel appears directly on the Zillow or Realtor.com page you're already looking at.
Long-term & short-term modes
Toggle between traditional rental math and Airbnb/Vrbo-style short-term analysis, with assumptions tuned for each.
Flags tab catches what's buried in the text
Undrly reads the listing's own description and calls out things like deferred maintenance or "as-is" language automatically - and shows you exactly where it found it.
Math tab shows every formula
No black box. See the full line-by-line calculation behind cash flow, cap rate, and every other number, so you can trust it instead of taking it on faith.
See every assumption
Vacancy, maintenance, closing costs, mortgage rate - every number driving the result is visible and adjustable, not a black box.
Resources tab, tailored to this address
One click to nearby comps, a real landlord insurance quote tool, walk score, and local rental law - plus save properties to compare and export a clean PDF report.
Always free

Long-term rental analysis - unlimited, no catch.

Cash flow, cap rate, cash-on-cash, break-even rent, the full math breakdown, every assumption adjustable - all of it is free on every listing, forever. Pro is only about unlocking short-term rentals; long-term analysis was never the upsell.

UNDRLY
Monthly Cash Flow
+$252/mo
SOLID
List Price
$299,000
6.5/10
Deal score· Better than 71% of the 12 LTR properties you’ve viewed5/7 verified
SummaryFlags 2MathAssumptionsResources
Cap Rate
6.7%
Cash-on-Cash
3.4%
Monthly PITI
$2,010
Break-even Rent
$2,311
Cash to Close
$89,751
Price / Sqft
$202
0.87% rent-to-price · near the 1% ruleRent basis: nearby 3-bed rental houses
What this could rent for
Median of 12 nearby 3-bed rental houses — applied as your rent estimate · size-adjusted: $1.76/sqft × 1,480 sqft · break-even $2,311/mo · tap a rent and watch the verdict move
Interactive example — real math, not a real listing. Try the three rents.
What you get

All of long-term, free. Pro buys the short-term data.

Long-term underwriting is unlimited and free, permanently — and free users can open short-term mode to see exactly what Pro measures. Pro exists because live short-term comps cost real money per lookup; that's what you're paying for.

Free forever
Underwrite any rental
No account. No card. Unlimited listings.
Cash flow, cap rate, cash-on-cash return
PITI and break-even rent
"What this could rent for" - a three-scenario rent ladder from real nearby comps, size-adjusted
Listing flag scan
Live 30-year mortgage rate
Data confidence breakdown
Save up to 5 properties
This is the entire product for long-term rentals. Nothing here is a trial or time-limited.
Pro
Short-term rentals, with real market data
$14.99
/mo · $149.99 yr
Tap once on any listing and Undrly pulls live Airbnb comps for that exact location — not a city-wide average.
Live Market PRO25 comps · AirROI
$247 at 68% booked · $5,106/mo gross
Occupancy68%
Pricing and revenue
Avg nightly
$247+6%
ADR range
$180–320
RevPAR
$167
Annual rev
$61.0k
Demand and occupancy
Occupancy
68%+3
Adjusted
64%
Booked
231/340
Avg stay
3.4 nt
Market and competition
Superhost
38%
Min stay
2 nt
Pro-managed
44%
Cleaning fee
$145
Guest experience
Comp rating
4.87
Reviews
96 avg
Guest favorite
31%
Capacity
8 guests
9 of 50 lookups used this month · resets in 21 days
Short-term rental mode
PDF underwriting report
Full math breakdown
Unlimited saved properties
Deal score percentile history
50 live lookups per month
Each lookup costs us money, so they're capped and you trigger them yourself — nothing is fetched in the background.
The Flags tab

It reads the listing so you don't have to.

Undrly scans the description text on every listing for risk language and notable positives, then shows you the exact sentence it found - so you can decide for yourself, not just take a score's word for it.

Illustrative example - not a real listing
Short-term rentals

See exactly what Pro unlocks.

Free shows you the shape of the deal. Pro fills in the real numbers - live nightly rate and occupancy pulled straight from AirROI, not a rough guess.

Free
Returns, the score, and live market data unlock with Pro
Undrly Pro
UNDRLY
Monthly Cash Flow
+$438/mo
SOLID
List Price
$399,000
6.8/10
Deal score· Better than 64% of the 9 STR properties you’ve viewed6/7 verified
SummaryFlags 3MathAssumptionsResources
Cap Rate
7.0%
Cash-on-Cash
3.9%
Monthly PITI
$2,957
Break-even ADR
$215/nt
Cash to Close
$135,592
Price / Sqft
$270
Live Market PRO25 comps · AirROI
$247 at 68% booked · $5,106/mo gross
Occupancy68%
Pricing and revenue
Avg nightly
$247+6%
ADR range
$180–320
RevPAR
$167
Annual rev
$61.0k
Demand and occupancy
Occupancy
68%+3
Adjusted
64%
Booked
231/340
Avg stay
3.4 nt
Market and competition
Superhost
38%
Min stay
2 nt
Pro-managed
44%
Cleaning fee
$145
Guest experience
Comp rating
4.87
Reviews
96 avg
Guest favorite
31%
Capacity
8 guests
9 of 50 lookups used this month · resets in 21 days
Interactive — tap a rate tier and watch the whole deal move. Real math on a sample listing.
Powered by AirROI

Real short-term rental data, not a rule of thumb.

Most rental calculators guess your nightly rate by doubling the long-term rent. Pro replaces that guess with an actual market check, pulled from AirROI's database of 20M+ real Airbnb listings across 190+ countries - the same data professional investors and lenders use to underwrite deals.

Matched to your exact property
Comps are filtered by bedroom, bathroom, and guest count - not a generic city-wide average that ignores what you're actually buying.
A full year of data, not a snapshot
Trailing-twelve-month figures, so a single busy weekend can't make a mediocre property look better than it really is.
Fully transparent methodology
See exactly how many comps went into the number and what the math behind it is - never an unexplained black-box figure.
You're always in control
Checking a listing is one click, one lookup - never automatic, never a surprise. 50 checks included every month, and you decide which properties are worth using one on.
The report

Take the numbers with you.

One click prints a clean underwriting snapshot for your lender, your partner, or your own file. Every estimate is labelled as one.

Undrly
Underwriting snapshot
1400 Club Dr · Long-Term Rental · Generated July 29, 2026
$312/mo
SOLID
Key metrics
List price$439,000
Monthly rent$2,350/mo
Cap rate5.9%
Cash-on-cash return4.2%
Monthly PITI$2,038/mo
Rent basis
SourceMedian of 8 nearby 3-bed rental houses
Comps range$1,900–$2,900
Data confidence — 3/6 verified
~ Property taxReassessment estimate
~ InsuranceState-average estimate
✓ Mortgage rateLive from FRED
It says where every number came from
Rent, tax, insurance and HOA each carry their source. Anything estimated rather than taken from the listing says so on the page, not in a footnote — including property tax, which Undrly deliberately estimates rather than copying the seller's bill.
It shows the rent basis, not just the rent
The comp set, the bedroom match, and the range behind the median — so whoever reads it can check your work instead of taking one number on faith.
It carries the flag scan
Including the exact wording that matched. If a listing's description couldn't be read at all, it says that too, rather than printing a clean bill of health it hasn't earned.
It prints or saves as a PDF
Opens as a plain page in a new tab, then Print to PDF. No account, no upload, nothing leaves your browser.
How it gathers data

Watch it work.

No database of our own, no scraping farm, no account. Four stages, all running in your browser on the page you already have open.

How Undrly gathers data Listing page $439,000 · 3bd · 1,559sf Rental listings 8 three-bed houses · median $2,350 FRED 30-yr fixed · 6.55% AirROI · Pro 42 short-term comps · on request Undrly in your browser Panel on the page +$312/mo · 5.9% cap PDF report 4 of 6 inputs verified
The listing page
$439,000
List price
3 bd · 2 ba · 1,559 sqft
Facts row
Annual Tax Amount: $3,512
Property details
“NEW ROOF 2024, public sewer…”
Description
Extracted
Price$439,000
Beds / baths3 / 2
Square feet1,559
Annual tax$3,512
Flag detectedRECENT ROOF
Nothing is fetched to do this. Tax and HOA are used only when the listing actually publishes them — otherwise they fall through to a state average, clearly marked.
36 nearby rentals → 8 real comps
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MEDIAN $2,350/mo
A rental search returns mostly apartment units, and a single large complex can supply dozens of them. Undrly drops those and keeps houses matching your listing's bedroom count, then takes the median of what survives.
Sources
Mortgage rateFRED LIVE
Property taxREASSESSED
InsuranceFL AVERAGE
HOAON LISTING
Monthly payment
Principal & interest$2,092
Taxes$293
Insurance$512
HOA$99
Rent − PITI+$312/mo
The 30-year rate comes from the Federal Reserve's FRED series, refreshed weekly. Anything greyed is substituted — a state average standing in for a figure this listing didn't publish.
Data confidence — 3 of 6 verified
PriceVERIFIED
Rent estimateVERIFIED
Property taxESTIMATED
InsuranceESTIMATED
HOAESTIMATED
Mortgage rateVERIFIED
What that means
Three of six inputs came straight from the listing or a live feed. The rest are estimates standing in until you supply a real figure.
Get a real insurance quote or your county's tax figure, type it into Assumptions, and those rows turn green. The deal score moves with them.
Every figure carries its source into the PDF report too. An estimate is always labelled as one — on the page, in the report, and in the math breakdown.
The honest limits. Rent comps are asking prices, not signed leases. Tax is a reassessment estimate from state averages — confirm the real figure with your county. Undrly screens deals in seconds; inspections, insurance quotes, and final diligence are still yours.
Property tax

The tax number on the listing isn't your tax number.

Most calculators copy the tax figure straight off the listing. That figure belongs to the person selling the house — and in states with a homestead exemption and an assessment cap, it can be a fraction of what the next owner pays.

What the listing says
$7,200/yr
The seller's current bill. Homestead exemption applied, assessed value capped over years of ownership.
What Undrly underwrites
$14,400/yr
Estimated after reassessment at the purchase price, with no homestead exemption — because an investor doesn't get one.
It changes the whole deal
On a property like the one above, the difference is roughly $600 a month. That's the gap between a deal that cash flows and one that doesn't — hidden inside a number most tools present as verified fact.
The seller's bill is a floor, not a forecast
Undrly takes the higher of the state-rate estimate and the seller's current bill. A reassessment moves taxes up at sale, essentially never down, so the published figure sets a minimum rather than an answer.
And it tells you it's an estimate
Property tax never shows as verified in the confidence breakdown, because it isn't. Pull the real figure from your county property appraiser, type it into Assumptions, and then it counts as verified.
Pricing

Long-term: free forever. Short-term: Pro.

Free isn't a trial - long-term underwriting never costs anything. Pro exists because short-term mode runs on licensed live market data that costs real money per check; the subscription covers 50 checks a month.

Monthly Annual Save ~17%
Free
Full long-term underwriting, on every listing, forever
$0
  • ✓ Unlimited long-term rental analysis
  • ✓ Instant 0-10 deal score on every listing
  • ✓ Cash flow, cap rate, and full math breakdown
  • ✓ Rent ladder - conservative / likely / optimistic rent from real nearby comps, with the cash flow each produces
  • ✓ Every assumption adjustable - vacancy, maintenance, closing costs, and more
  • ✓ Live 30-year mortgage rate from FRED, always current
  • ✓ Save up to 5 properties
  • - Short-term rental cap rate & cash-on-cash
  • - Live nightly rate & occupancy data
  • - Export polished PDF reports
Add to Chrome — free
Works on Zillow and Realtor.com. No account needed.
Best for active investors
Undrly Pro
For anyone seriously evaluating short-term rentals
$14.99/month
  • ✓ Everything in Free, unlocked in full
  • ✓ Full short-term rental economics - cap rate, cash-on-cash, break-even ADR
  • ✓ Live Airbnb market data from AirROI - real rates, occupancy, revenue, fees & competition, 16 stats per market
  • ✓ 50 market checks a month - rechecking a property you've already pulled is always free
  • ✓ Full math breakdown for every STR number
  • ✓ Export polished PDF reports for lenders or partners
  • ✓ Unlimited saved properties
  • ✓ Direct email support from the person who builds it
  • ✓ Cancel anytime - no contracts
Get Undrly Pro
You'll get a license key at checkout. Install the extension first — the key is activated inside it.
One property you correctly pass on pays for years of Pro.
Support

Billing, installing, and how your data's used.

Undrly is an independent product - you're talking to the person who built it, not a support queue.

Does checking the same listing twice use two lookups?
No. Once you've checked a property, Undrly keeps that result for two weeks - revisiting the listing, reloading the page, or coming back tomorrow costs nothing and doesn't touch your monthly allowance. A lookup is only spent the first time you check a given property.
What does Pro's monthly lookup limit actually cover?
Pro includes 50 live market checks per month. Each one is a deliberate click - Undrly never spends a lookup automatically just because you opened a listing - and repeat checks of the same property are free, so 50 goes further than it sounds. Long-term rental analysis, flags, saved properties, and PDF reports have no limit at all.
Why doesn't property tax show as verified?
Because the figure on a listing is the current owner's bill, not yours. Homestead exemptions and assessment caps end when a property sells, and an investor doesn't qualify for a homestead exemption at all - so Undrly estimates the reassessed amount rather than copying a number that describes someone who's leaving. It's labelled an estimate because it is one. Enter the real figure from your county property appraiser in Assumptions and it'll count as verified. More on how this works.
Which numbers are real, and which are estimated?
Price comes straight off the listing. The mortgage rate is live from the Federal Reserve. Pro's nightly rate and occupancy come from real comparable Airbnb listings. Property tax and insurance are estimates until you enter your own figures, and if a listing publishes no rent estimate, Undrly falls back to a rough rule of thumb and says so. Every one of these carries its source in the Data Confidence breakdown - nothing estimated is dressed up as a fact.
Can I use Pro on more than one computer?
A licence activates on one device at a time. If you move to a new machine, it'll transfer across on its own once the old one has been idle for a couple of weeks - and if you need it sooner than that, email support at undrly dot app and we'll release it right away.
How do I cancel or update my subscription?
Manage your subscription here - cancel, switch plans, or update your card, no waiting on a reply. Canceling stops future billing but doesn't refund time you've already paid for: on the monthly plan you keep Pro through the end of your current month, and on the annual plan you keep Pro through the end of your current year. For anything else, email support at undrly dot app.
Where do I download Undrly?
Undrly is a Chrome browser extension. If it's not yet listed on the Chrome Web Store, contact support at undrly dot app for install instructions.
What data does Undrly use?
Property details (price, rent estimate, taxes) come from the listing page itself. Pro short-term rental estimates use market data from AirROI. Undrly does not sell or share your personal information. Full details in our Privacy Policy.
How is the live nightly rate calculated?
When you click to check a listing, Undrly pulls the actual nearby comparable Airbnb listings (matched by bedroom, bathroom, and guest count) and averages their trailing-twelve-month nightly rate and occupancy. That's a real full-year figure, not a guess - but it blends peak and off-season together into one number, so it can run higher than a typical night in markets with a strong peak season. It's meant as a solid starting point to sanity-check against, not the final word - if you know the market better (or own the property), you can always type in your own number and Undrly will use that instead.