How to choose a real estate data platform

Real estate and property analytics tools split cleanly into two groups: free aggregate datasets that track market trends, and commercial property-data businesses that sell parcel-level, ownership or valuation records to build on. Which one you need depends on whether the question is about a market or about a specific asset.

Aggregate market trend vs. parcel-level property records

Redfin Data Center and Zillow Research are free, downloadable datasets — home price indices, inventory, days-on-market, migration and affordability trends — at national, state, metro, county and, for Zillow, ZIP-code level, drawn from each company's own brokerage or listing data. Neither gives you a record for a specific property; they're built for understanding a market, not underwriting a deal. If your question is "what's happening to home prices in this metro," start here before paying for anything.

Everything else in the category deals in records tied to individual properties or specific transactions: tax assessments, deeds, mortgages, ownership, leases, comps, valuations. That's a fundamentally different, and generally paid, kind of data, and data quality — how current and how verified each record is — matters far more once you're relying on it for a specific asset.

What the paid property-data businesses each specialize in

None of the four paid providers directly compete on the same job — they specialize by property type and by which part of the property lifecycle they cover:

• ATTOM is the broadest by coverage: nationwide tax, deed, mortgage, foreclosure and valuation-model data licensed in bulk, as files, an API, or via AWS or Snowflake marketplace listings, for companies building their own products on top — proptech, lenders, insurers. It's infrastructure, not an end-user analytics application.
• CoStar is commercial real estate specifically: verified property, lease and sale comp data built by a large research staff, sold as the CoStar Suite research subscription to brokers, appraisers and investors, and cross-fed by CoStar's own Apartments.com and LoopNet marketplaces.
• HouseCanary is residential valuation and forecasting: automated valuation models, rental estimates and predictive price forecasts for individual homes, sold as self-serve reports and a usage-priced API to agents, appraisers, lenders and single-family-rental investors.
• Reonomy is commercial ownership resolution: unmasking who actually owns a property, including LLCs and shell companies, for brokers, lenders and investors sourcing off-market deals, distinct from CoStar's strength in verified lease and sale comps.

A commercial broker sourcing off-market deals wants Reonomy; the same broker pulling lease comps for a pitch wants CoStar; a mortgage or insurance company building an underwriting product wants ATTOM's bulk records; an agent or lender pricing a single home wants HouseCanary. These aren't substitutes for each other in most workflows — check whether you actually need more than one.

Deployment: end-user tool vs. data to build on

This is a meaningful split within the paid group. HouseCanary, CoStar and Reonomy are sold as end-user software — a person logs in, searches, pulls a report. ATTOM is different: it's licensed as bulk files, API access or a data-marketplace listing for another company's engineering team to build into their own product. If you need a person to research individual properties, you want one of the first three; if you need standardized nationwide records to power something you're building, ATTOM is the more direct fit, though it requires engineering effort to integrate rather than a login.

How pricing works

Redfin Data Center and Zillow Research cost nothing and require no account. Every paid provider here prices by quote — data licensing, subscription seats or usage — with the partial exception of HouseCanary, which publishes self-serve monthly and annual tiers alongside custom Enterprise and API pricing. None of the commercial-focused providers, ATTOM, CoStar or Reonomy, publish rate cards; expect a sales conversation scoped to your geography and data volume.

A shortlist by situation

• Tracking a metro or national housing market, no budget: Redfin Data Center or Zillow Research — check both, since methodology and cadence differ.
• Building a product that needs nationwide parcel-level records: ATTOM, licensed in bulk or via API.
• Commercial brokerage, appraisal or investment research: CoStar for verified comps and market trends.
• Sourcing off-market commercial deals or unmasking ownership: Reonomy.
• Valuing or forecasting individual residential properties: HouseCanary, self-serve or via API depending on volume.

Questions to ask vendors

• Is this a self-serve tool for individual research, or bulk or API data meant to be built into our own product?
• How is the underlying data sourced and refreshed, such as county recorders, MLS feeds or proprietary research staff, and how current is it?
• For AVMs and forecasts: what's the published accuracy or confidence range, and on what property types was it validated?
• Does pricing scale by geography, seats, API calls or property count, and what does that cost at our expected volume?
• Can data be exported or integrated into our existing systems, such as a loan origination system, CRM or warehouse?

Common mistakes

Paying for a commercial data subscription when a free aggregate dataset would answer the actual question is a common overspend — "is this market cooling" doesn't need parcel-level records, and Redfin Data Center or Zillow Research covers it, ideally shown with proper visualization of the trend rather than a single number. The reverse mistake is trying to underwrite a specific deal or file from aggregate market-trend data, which was never built for that resolution. And buying CoStar for ownership research or Reonomy for verified lease comps is buying the wrong specialist — check each provider's actual strengths before assuming they're interchangeable commercial-data tools.

See CoStar vs Reonomy and Redfin Data Center vs Zillow Research for two common head-to-head decisions, and every tool in this category.