Katastr nemovitostí

The katastr nemovitostí is the Czech equivalent of a land registry. Every property in the country is recorded with its owner, mortgages, easements, and legal restrictions. Anyone can look up any property for free.

If you want to verify that a landlord actually owns the flat they're renting to you, ask for the cadastral number (číslo popisné and the parcel number) and look it up. This is one of the strongest scam filters available.