If you need to check other person / firm - go to national register of insolvent debtors (KRDN) - krdn.pl
This service is payable.
KRDN grants anyone the fast and unrestricted access to information for people and businesses registered in the judicial Register of Insolvent Debtors. This register was established under the Act of August 20, 1997 of National Court Register in order to ensure the safety and security of business transactions. Register of Insolvent Debtors allows immediate verification of the reliability of the people in the private and economic relations, and is also an excellent tool for effective claims pursuing.
In our country, the data on debtors gather information bureaus (BIG). Currently, in our market works three such offices:
Krajowy Rejestr Długów
Rejestr Dłużników ERIF
But there you can get data about yourself (pesel required) or a company - once in 6 month the service is free.