I would like to find out if I can use the API site CIAN.ru
It is not written in public about the API, but I was able to find an example of using at one of the cyan services. Here is the example of links

You need it to automatically add apartments to the database of my site uploading lists from this very API

Does this not contradict any licenses?

Answer 1, Authority 100%

If there are no public documents on the API, then you, of course, can use them, only here is the problem – developers can change it at any time and your project will break.

Moreover, the licensing agreement CIAN.ru lies here . As I understand it, the use of their API falls under the point:

7.2.3. use without special sites on the permission of the administration of sites automated scripts (programs) to collect information on
Sites and / or interaction with sites and their functional;

So if the data from there is really needed for a serious project on a systematic basis – I recommend contacting developers.