What is the main difference between CoStar and Reonomy?

CoStar is a market data and analytics platform — it covers listings, verified sale and lease comps, submarket trends (rent, vacancy, absorption), and tenant data, primarily for research, valuation, and on-market deal flow. Reonomy (now part of Altus) is an ownership and contact intelligence platform — it identifies who owns a property, resolves the entities behind shell LLCs, maps owner portfolios, and provides contact data for direct-to-owner, off-market sourcing. CoStar is a research tool; Reonomy is a prospecting tool. They solve opposite ends of the deal funnel and are often used together rather than as substitutes.

Should I use CoStar or Reonomy for off-market deal sourcing?

Reonomy is the stronger choice for off-market sourcing. It's purpose-built to surface unlisted assets that match a buy-box, identify the real owners behind LLCs through entity resolution, map an owner's full portfolio, and supply contact data (phones and emails) to start direct outreach. CoStar excels at on-market listings, comps, and analytics, but it isn't designed to power direct-to-owner prospecting at that depth. If proprietary, off-market deal flow is your goal, Reonomy fits the workflow; pair it with skip-trace and signal-monitoring automation to prioritize which owners are most likely to transact.

Does CoStar have an API I can integrate with?

No. CoStar does not offer a sanctioned public API, and its terms of service prohibit automated, programmatic, or scraped access to its data — a position it has litigated and actively enforces. Any product claiming a direct 'CoStar integration' is misrepresenting what is technically and legally permissible. The compliant approach is works-alongside: your team exports data under your own CoStar license, and automation tools ingest those exports. You get AI value from the data without violating the terms.

Does Reonomy offer API access for automation?

Yes, but it's partner-gated and customer-licensed. Reonomy provides API access to its ownership, parcel, and contact data under your subscription, typically through a partner program rather than a self-service signup. The data carries redistribution restrictions — you can use it within your own organization and workflows, but you cannot resell or republish it. That makes it suitable for building an internal enrichment and sourcing pipeline, which is exactly where automation adds the most value on top of Reonomy.

Which has better ownership and contact data, CoStar or Reonomy?

Reonomy. Ownership intelligence and contact data are its core product — resolving parcels to the real people and companies behind shell entities, mapping full owner portfolios, and providing phone numbers and emails for outreach. CoStar carries some ownership information, but contact data and entity resolution for direct outreach are not its focus. If your workflow depends on reaching owners directly for off-market deals, Reonomy is the clear winner on this dimension.

How much do CoStar and Reonomy cost?

Both are premium enterprise platforms priced by negotiation — based on geographic coverage, modules, seat count, and contract term — so there is no fixed public price for either, and any quoted figure would likely be wrong for your situation. CoStar is typically a larger, seat-based enterprise commitment; Reonomy is a subscription that varies by coverage and users. Treat both as significant annual spend and request a quote scoped to your specific buy-box and team size rather than relying on a list price.

Can I use CoStar and Reonomy together?

Yes, and many serious acquisitions teams do. Because they cover different parts of the funnel, they complement rather than compete: Reonomy drives off-market discovery and owner outreach at the top of the funnel, while CoStar provides comps, analytics, and validation through underwriting and IC. The practical challenge is that the two datasets don't natively talk to each other. A property-enrichment pipeline can normalize and de-duplicate records across both — under each vendor's access rules — so your team works one clean, scored target list instead of two separate subscriptions.

How does AI automation add value on top of CoStar or Reonomy?

AI automation sits above whichever platform you license and turns its data into action faster. On the enrichment side, it cleans, normalizes, de-duplicates, and scores records against your buy-box, appending parcel data (e.g., ATTOM) and lease comps (e.g., CompStak). On the sourcing side, compliant skip-trace enriches owner contacts and a signal-monitoring agent flags which owners are most likely to transact. It respects each vendor's rules — CoStar works-alongside only via your own exports, Reonomy under your own license with no redistribution — so you get speed without crossing the terms of service.

CoStar vs Reonomy: Property Intelligence & Ownership Data Compared (2026)

If you're an acquisitions or research lead deciding between CoStar and Reonomy, the first thing to know is that this is not a like-for-like fight. CoStar and Reonomy answer different questions. CoStar tells you what's on the market, what comparable assets traded for, and how a submarket is performing. Reonomy tells you who owns a building, how to reach them, and which off-market properties match a buy-box — before anything is listed. Acquisitions teams that frame the decision as "which one wins" usually end up picking the wrong tool for the job in front of them.

This guide compares the two honestly, on real merit, and names a winner per use-case rather than declaring a single victor. We'll be direct about the constraints both carry: CoStar has no sanctioned API and its terms of service prohibit automated or programmatic access (a position it has litigated and enforces). Reonomy (now part of Altus Group) is customer-licensed with redistribution restrictions — its data and partner-gated API are available under your own subscription and cannot be resold or republished. Neither of those facts is a knock on the products; they're the rules of engagement you need to plan around.

One note on positioning: NextAutomation does not compete with either platform. We're the AI/automation layer that sits on top of whichever data source you license — enriching records, running compliant skip-trace, and turning raw ownership and comp data into a working sourcing pipeline. This comparison is objective first. Where automation changes the math, we'll say so plainly.

CoStar vs Reonomy at a Glance

Dimension	CoStar	Reonomy (Altus)
Primary strength	Listings, sale/lease comps, submarket analytics, tenant data	Ownership records, contact data, off-market property discovery
Core buyer use	Market research, valuation context, on-market deal flow	Off-market sourcing, owner outreach, portfolio mapping
Data breadth	Broadest in CRE — verified by a large research staff	Deep on ownership/parcel + entity resolution across the U.S.
Analytics depth	Strong — rent trends, vacancy, absorption, forecasts	Lighter — focused on discovery and ownership, not market analytics
Contact / skip-trace data	Limited — not its core purpose	Core strength — owner names, entities, phones, emails
API access	None sanctioned — ToS prohibits automated access	Partner-gated API under your license; no redistribution
Integration tier	Works-alongside only (export under your own license)	Customer-licensed / partner-gated
Pricing posture	Premium, seat-based enterprise contracts	Subscription, varies by coverage and seats

We've deliberately left specific dollar figures out — both vendors price by negotiation, market, seat count, and module, and any number we quoted would be wrong for your situation. Treat both as premium enterprise spend and get a quote scoped to your buy-box.

Buyer Decision Criteria: What You're Actually Choosing Between

The right starting question isn't "CoStar or Reonomy?" — it's "what part of my deal funnel is broken?" The two tools map to opposite ends of the sourcing problem.

Market analytics & listings (CoStar's lane)

If your team needs to understand a submarket — current rents, vacancy and absorption trends, recent sale and lease comps, tenant rosters, and what's actively on the market — CoStar is the deepest dataset in commercial real estate. Its research operation verifies listings and comps at a scale no competitor matches, which is exactly why lenders, brokers, and institutional buyers treat CoStar comps as a common reference point. For valuation context, market reports, and on-market deal flow, this breadth is the product.

Ownership & contact data for off-market (Reonomy's lane)

If your problem is finding deals that aren't listed yet — identifying who owns a target asset, untangling the LLC behind it, mapping an owner's full portfolio, and getting a phone number or email to start a conversation — Reonomy is purpose-built for that workflow. Its entity resolution (connecting parcels to the real people and companies behind shell entities) and its contact data are the reasons sourcing teams license it. CoStar simply isn't designed to power direct-to-owner outreach at that depth.

The deciding questions

On-market or off-market? If you buy mostly brokered, on-market deals and need comps and analytics to underwrite them, lean CoStar. If you generate proprietary deal flow by going direct to owners, lean Reonomy.
Research vs. outreach? CoStar is a research and valuation tool. Reonomy is a prospecting and outreach tool. Be honest about which job is the bottleneck.
Do you need contact data? Owner phones and emails are Reonomy's core; they are not CoStar's.
Do you need analytics depth? Rent trends, forecasts, and absorption are CoStar's core; they are not Reonomy's.
Will you automate on top of it? CoStar cannot be wired up programmatically — period. Reonomy can, under a partner-gated license. If automation is part of the plan, that distinction is decisive.

The Honest Head-to-Head — Winners by Use-Case

Rather than crown a single winner, here's the verdict per job. The right answer is whichever tool matches the work in front of you.

Use-case	Winner	Why
Sale & lease comps for underwriting	CoStar	Broadest verified comp set; the institutional reference standard.
Submarket analytics & forecasts	CoStar	Rent, vacancy, absorption, and forecasting depth Reonomy doesn't try to match.
On-market listings & tenant data	CoStar	Largest verified listing inventory and tenant rosters in CRE.
Off-market property discovery	Reonomy	Built to surface unlisted assets matching a buy-box across ownership and parcel data.
Owner identification & entity resolution	Reonomy	Untangles LLCs to the real owners and maps full portfolios.
Direct-to-owner contact / outreach	Reonomy	Owner phones/emails are core; CoStar isn't designed for this.
Programmatic / API access	Reonomy	Partner-gated API under license; CoStar has no sanctioned API at all.
Whole-of-market authority & brand	CoStar	Counterparties expect CoStar; it's the de facto market language.

The pragmatic read: CoStar wins on breadth, analytics, and comps; Reonomy wins on ownership, contacts, off-market discovery, and the ability to be automated. Many serious acquisitions shops license both — CoStar for the on-market and underwriting side, Reonomy for the off-market sourcing side — because they're complements, not substitutes. If budget forces one, let your deal-generation strategy decide: brokered buyers lean CoStar, direct-to-owner buyers lean Reonomy.

For the wider field — CompStak for crowdsourced lease comps, Cherre for data unification, ATTOM for nationwide parcel/ownership APIs, and Crexi for marketplace coverage — see our broader breakdown in Best CRE market-data and comps platforms.

Where AI Changes the Answer

Here's the part most buyers miss: the value of either platform is capped by how fast your team can turn its data into deals. A CoStar export sitting in a folder doesn't source anything. A Reonomy owner list nobody calls doesn't either. The bottleneck isn't the data — it's the work between the data and a live conversation. That's where automation reshapes the comparison.

Property enrichment on top of either source

Whatever you license, the raw records need to be cleaned, normalized, deduplicated, and matched against your buy-box. A property-enrichment pipeline takes CoStar exports (handled under your own license — never scraped, since CoStar's ToS prohibits automated access) or Reonomy's partner-gated API feed and turns scattered records into a structured, scored target list. It can append parcel data from ATTOM, layer in lease comps from CompStak, and resolve duplicate ownership entities — so your analysts work one clean list instead of three messy ones.

Skip-trace and off-market sourcing

Reonomy gives you owner identity and contacts; the next mile is reaching the right decision-maker and keeping the outreach organized. Compliant skip-trace automation enriches owner records with current contact paths, and an off-market deal-sourcing engine monitors signals — ownership tenure, debt maturity proxies, permit activity, assessed-value changes — to flag which owners are most likely to transact. That converts a static ownership database into a prioritized weekly call list. None of it requires touching CoStar's data; it runs on your licensed Reonomy feed plus public signal sources.

Continuous sourcing across both

If you run both platforms, an AI deal-sourcing agent can watch CoStar-side on-market activity (from your own exports) alongside Reonomy-driven off-market signals, score every opportunity against your acquisition criteria, and surface matched deals before a broker blast reaches your inbox. The automation sits above your subscriptions — it doesn't replace them, and it respects each vendor's access rules: CoStar works-alongside only, Reonomy under your own license with no redistribution.

Lifecycle Fit: Where Each Lands in the Deal Funnel

Both tools live primarily in the sourcing and early-underwriting stages, but they play different roles as a deal moves downstream.

Sourcing: Reonomy is the off-market engine — find unlisted assets, identify owners, build the outreach list. CoStar covers the on-market side — what's listed and who's marketing it. This is where the choice matters most.
Underwriting: CoStar takes over — sale/lease comps, rent and vacancy trends, and submarket forecasts feed the model. Reonomy's role fades here; it's a discovery tool, not a valuation tool.
IC & Diligence: CoStar comps and market reports support the investment memo and validate assumptions. Reonomy ownership history can confirm seller motivation and transaction context.
Capital Raise: CoStar submarket data strengthens the deal narrative for LPs. Neither tool is built for the raise itself — that's a separate workflow.
Asset Management & IR: CoStar's ongoing market data informs hold/sell decisions and quarterly LP context. Reonomy can monitor neighboring ownership for future bolt-on acquisitions.

The clean way to think about it: Reonomy fills the top of the funnel (off-market discovery and outreach); CoStar carries the middle (comps, analytics, validation). Automation is what connects them into one continuous pipeline instead of two disconnected subscriptions.

The Verdict

There is no single winner because they aren't the same product. If your deal flow is brokered and on-market and you need comps, analytics, and the dataset your counterparties already speak, choose CoStar. If you generate proprietary deals by going direct to owners and need ownership intelligence, contact data, and the ability to automate, choose Reonomy. If you can fund both — and serious acquisitions teams often do — run them as complements: CoStar for the on-market and underwriting side, Reonomy for the off-market sourcing side.

Whichever you pick, the data is only as valuable as your ability to act on it. The honest constraints are real: CoStar is works-alongside only (no API, ToS prohibits automated access), and Reonomy is customer-licensed with no redistribution. Within those rules, a property-enrichment and off-market sourcing layer is what turns either subscription into a deal machine.

For the full picture, see our pillar guide The Complete CRE Software Stack, the category breakdown in Best CRE market-data and comps platforms, and the integration details for CoStar and Reonomy. If you want to map which automations give your firm the fastest payback on the data you already license, our free roadmap call is the right starting point.