CoStar Group is the dominant commercial and residential real estate data, analytics, and marketplace company. The portfolio spans the flagship CoStar commercial real estate intelligence platform, LoopNet (CRE marketplace), Apartments.com network (residential rentals, including ForRent.com and Westside Rentals), Homes.com and Homesnap (for-sale residential), Ten-X (online CRE auctions), BizBuySell (business-for-sale marketplace), STR (hotel data), Visual Lease (lease management), Matterport (3D spatial capture), and international properties including OnTheMarket (UK), Emporis (Germany), and a controlling stake in Domain Group (Australia). Distribution to partners is via enterprise data licensing, syndication feeds, and brand-specific marketplace tooling rather than a public self-serve developer portal.
CoStar Group is listed with 14 APIs on the APIs.io network. Tagged areas include Commercial Real Estate, Residential Real Estate, Real Estate Data, Marketplace, and Analytics.
CoStar Group’s developer surface includes product news and 16 more developer resources.
Regulatory Posture applies to this provider. Its tags matched the
Horizontal (data, software, accessibility, platform) regime, so
Regulatory Posture carries 15 points of the composite.
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applicability map is public and we will correct it.
Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for
this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero:
never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and
several others — scorable at all.
The six quality facets above are damped to 85 points between them,
because the conditional facet above carries the other
15. That is why each facet's contribution is shown against a damped
maximum: raising a quality facet moves the composite by 85% of its nominal
weight, not 100%. The full arithmetic is at apis.io/rating/.
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Agent readiness — checks not met, largest first (exact, from this profile):
Machine-Readable Auth+10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency+9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics+8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
11 more unmet checks in the Agent Readiness table above.
Kin Score — facets with the most composite points still available (weight × headroom):
CoStar's flagship commercial real estate information platform covering property, tenant, lease, sale, and market analytics across office, industrial, retail, multifamily, and sp...
Residential rental marketplace network including Apartments.com, ForRent.com, and Westside Rentals, providing listings, leads, and advertising to multifamily owners and managers.
Land-for-sale marketplace network covering rural, ranch, recreational, and development land in the United States.
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CoStar Group API pricing
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