Undrly — Rental Property Underwriting

Instant cash flow, cap rate, and cash-on-cash return estimates on Zillow and Realtor.com listings.

Stop copying listing numbers into spreadsheets. Undrly puts the full investment analysis directly on the page — open any house for sale on Zillow or Realtor.com and the numbers are just there. On every listing, instantly: Monthly cash flow after ALL costs — mortgage, taxes, insurance, vacancy, maintenance Cap rate, cash-on-cash return, and break-even rent What it could realistically rent for, based on nearby rental listings An honest verdict — including PASS when a deal loses money Seller position: what they paid, their estimated equity, and your negotiating room Flags for what's buried in the description — as-is sales, roof age, flood mentions, HOA fees Test your own deal, not the asking price. Edit the price to what you'd actually offer, adjust the down payment, tap a rent scenario — everything recalculates instantly. Your inputs are remembered per listing, and you can save properties into a sortable shortlist. Long-term rental analysis is free. Forever. No account, no card, no trial clock. Undrly Pro adds Short-Term Rental mode — live Airbnb market data for any listing you're viewing: real nightly rates, occupancy, revenue, and what the competition charges, from comparable rentals around that exact address. Compare "rent it long-term vs. list it on Airbnb" on the same house, with rate-strategy scenarios and 50 live market checks per month. Private by design. All analysis runs in your browser. Undrly doesn't track your browsing, collect analytics, or transmit the pages you visit — see the privacy policy for the full plain-English version. Built by a solo developer and rental investor who got tired of the spreadsheet grind. Made for beginner and intermediate investors: every number is explained in plain English, with a full walkthrough at undrly.app/guide.html. Undrly is an analysis tool, not financial advice — estimates should be verified before any purchase. Not affiliated with Zillow or Realtor.com.