CoStar

Brokers, appraisers, and investors use it to look up buildings, find comparable sales, and see rents and vacancy trends. It also owns listing sites such as Apartments.com and LoopNet. Coverage is deepest in the US and parts of Europe.

Subscriptions are costly and aimed at professionals. Data quality depends on research teams and submissions, so appraisers still verify key facts.

Reonomy and Cotality are other data sources. CoStar suits appraisers and commercial brokers.