https://www.epo.org/en/service-support/faq/searching-patents/european-patent-register-and-federated-register/european-0

What is the European Patent Register?

The European Patent Register (the Register) is the official place where the European Patent Office stores all publicly accessible documentation and legal status information on European patent applications, European patent applications with unitary effect and Euro-PCT patent applications as they pass through the various stages of the patent grant procedure, including opposition and certain details of the appeal and post-grant procedures.  

Post-grant information is available in the Unitary Patent section of the Register. If there is no European patent with unitary effect, you can access post-grant information in the EP Legal status view and access the corresponding national registers via deep links (where available). A quick overview of post-grant information, including for European patents with unitary effect, is available in the EP Federated register view. The European Patent Register is free of charge