Property analysis built from public records, not guesswork
Comp-supported valuation, tax projection, school ratings, flood risk, condition assessment, and a blunt honest opinion — for any Illinois, Michigan, Missouri, or New York State residential property, in under two minutes.
Analyze a property →No account needed to run an address and see the summary.
Comp-supported valuation
A defensible price range built from actual comparable sales in the area — not a single black-box number.
Post-sale tax projection
What your property tax bill actually becomes after a purchase closes — Cook County's real reassessment timeline in Illinois, Proposal A's assessment-uncapping rule in Michigan, Missouri's fixed odd-year reassessment cycle (a sale doesn't trigger one), and New York's roll-based estimate (a sale doesn't reassess a property there either, so the report shows today's assessment and what a revaluation at your price would give).
Condition & flip detection
Permit history, assessor records, and price history cross-checked to flag flips, unpermitted work, and overpricing.
An honest opinion
Every report ends with a blunt, plain-English verdict — not a sales pitch, and not a recommendation to buy or not buy.
How it works
Enter an address
We resolve it to a real parcel, then pull assessor records, sales history, permits, school ratings, and flood data. A free summary and an honest read come back before you commit to anything.
Confirm what we can't see
Public records don't know the asking price or whether the kitchen was redone last year. Answer as few or as many optional questions as you like — each one narrows the range and raises the confidence label.
Get the full report
About 90 seconds later you have the complete analysis — comps, tax scenarios, condition assessment, due-diligence checklist. Download it as a PDF or ask follow-up questions about it.
See a real report
This is an actual published summary — valuation range, condition read, current and projected tax, school ratings, the confidence label, and what would tighten the analysis. Nothing staged.
6531 S Drexel Ave, Chicago
Cook County — the deepest data coverage, including the public comp engine, assessor condition rating, permit history, and per-school profiles.
View the sample report →What’s in a full report
Around nineteen sections, adapted to the property and to whether you’re buying, selling, or evaluating it as an investment.
Valuation
- Comparable sales with $/sqft normalization
- Price positioning vs. the comp range
- Price history and prior-sale context
- Flip detection and implied renovation margin
Money
- Post-sale tax projection across four scenarios
- Cash to close and monthly carrying cost
- Rent estimate, gross yield, and cap-rate proxy
- Financing scenarios at current benchmark rates
Condition & risk
- Condition tier from assessor and permit evidence
- Public records vs. listing discrepancies
- Flood zone, environmental hazards, transit
- Schools, and a due-diligence checklist to work from
- Everyday places within half a mile (grocery, parks, pharmacy, and more)
Where the data comes from
Reports are built from government and public records, with licensed market data filling the gaps public sources don’t reach. Every figure carries its provenance, and a gap is reported as a gap rather than filled with a guess.
Cook County & City of Chicago open data
Parcel records, assessor characteristics and condition ratings, arm's-length sales, building permits, code violations, and per-school CPS profiles.
Illinois Department of Revenue
MyDec transfer declarations for statewide arm's-length sale records, plus the annual county equalization factors.
Illinois State Board of Education
The 2025 Report Card — proficiency, graduation rates, absenteeism, and per-pupil spending for all 864 Illinois districts.
Michigan city, county and state sources
Where a city or county publishes its own assessing roll — Detroit, Ann Arbor, Grand Rapids, and Wayne, Oakland, Macomb, Ottawa, Kent, and Jackson counties — the parcel's State Equalized Value and Taxable Value, combined with the Michigan Department of Treasury's published millage rates for a real post-sale Proposal A tax projection. Elsewhere in Michigan the estimate rests on the most recent recorded assessment and says so. Plus EGLE contamination records and state education outcomes.
Missouri county assessors, collectors and DESE
Where a county publishes its own roll or levies — St. Louis County and City, Jackson, Clay, St. Charles, Greene, and Boone counties — the parcel's assessed value or tax district and the published levies behind a bill estimate, plus the state education department's district outcomes. Kansas City, St. Louis, and St. Charles police data for crime near a property.
New York State assessment rolls, tax rates and education data
The State's published assessment roll read by address, with the State's county, town and school tax rates for a tax estimate (village and special-district taxes are in no statewide source, so the estimate can run about 10% low, and the report says so), NYSED school outcomes, and DEC remediation sites. It covers New York City's five boroughs too, from the city's own Department of Finance roll, building records, schools and police data.
Overture Maps Foundation
A snapshot of everyday places — grocery stores, pharmacies, parks, coffee shops, gyms, libraries and hospitals — counted within half a mile of a property. It is described, never used to value the property, and it can omit a business or still list one that has closed.
U.S. Census Bureau
TIGERweb school-district boundaries resolved by point-in-polygon, and American Community Survey neighborhood data.
FEMA
National Flood Hazard Layer flood zone and special-flood-hazard-area determination.
HUD
Small Area Fair Market Rents behind the rent model, plus affordable-housing and inspection-score datasets.
Federal Reserve (FRED)
Mortgage benchmark rates, the FHFA house price index, and county-level market trend data.
Common questions
What does it cost to try?
Running an address and seeing the summary and honest opinion costs nothing, and doesn't require an account or a card. Signing in is only needed to save an analysis, compare properties, or ask follow-up questions.
How accurate is the valuation?
It's a probabilistic range, not an appraisal. The range is calibrated on past sales: it is built so that about 55 of every 100 sale prices land inside it, which means a sale will fall outside it nearly half the time, and a wide range is the model telling you it is unsure. The typical miss of the midpoint runs from about 10% of the price in the best-measured markets to about 30% in the hardest (Detroit, Flint, and small New York cities). Every report also carries a first-class Analysis Confidence label that tells you how much weight it deserves. A thin comp pool or an undetermined condition gets labeled Low — we'd rather say the analysis is weak than quietly hand you a confident-looking number built on two sales.
Which areas are covered?
All 102 Illinois counties, plus Michigan, Missouri, and New York State, including New York City. Depth varies: Cook County properties get the fullest treatment, since the county publishes parcel, assessor, sales, permit, and violation data we can build a comp engine directly on top of. Other Illinois counties draw on statewide and federal sources plus licensed market data. Michigan is newer and leaner — real per-parcel tax and assessment data where a city's or county's own records are public, the State's published millage rates and statewide school outcomes, plus federal sources and licensed market data. Detroit and Flint carry a Low confidence label because recorded prices there span an extreme range and public records cannot see the condition behind it, and the Upper Peninsula, where few homes sell, comes with a note that its range is rougher. Missouri is the leanest of the three: it leans on licensed market data for most counties, with real public sources where a county or city publishes them — the St. Louis, Jackson, Clay, St. Charles, Greene, and Boone county tax data, state school-district outcomes, and crime and permit data for a few cities. Missouri does not record sale prices publicly, so comparable-sale pools there are thinner. New York State is the newest: the tax estimate is built from the State's assessment roll and published rates, valuation ranges are measured region by region, and small cities and rural counties carry a Low confidence label because the comparable-sale evidence there is weaker. In New York City, a condominium is valued from the city's own value for the unit and its building's recent sales, and carries a Low confidence label when the building has too few sales for that; co-ops and rental buildings carry a Low confidence label because the city's sales file records no apartment label or rent roll; one- to three-family houses are measured directly. A report always says plainly when a section is thinner because the data isn't there yet, rather than filling the gap with a guess.
Will it tell me whether to buy?
No, and that's deliberate. Reports never recommend buying or passing. They lay out what the data supports, flag what's uncertain, and name the risks worth verifying — the decision stays yours.
Is this an appraisal or a broker's opinion?
Neither. CompBasis is not a licensed real estate broker, salesperson, or appraiser, and a report is not an appraisal, a comparative market analysis prepared by a licensee, or a substitute for a home inspection. It's research to inform your own judgment.
What if something in a report looks wrong?
Every report has a button to flag it. Public records genuinely do contain errors — mis-recorded square footage, stale property classifications, missing permits — and reports say when a figure looks inconsistent rather than papering over it.
Read up first
Run an address
Covers all 102 Illinois counties, plus Michigan, Missouri, and New York State, including New York City. Built for buyers, sellers, and investors researching a property. Never recommends buy or don't buy — the analysis is yours to act on.
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