One of the country-specific verification apps is required to display the EU Digital Covid Certificate (EU DCC) QR code. There is no single app throughout the EU for this. The apps available in Germany, for example, are CovPass and Corona-Warn-App.
The following country overview shows apps that can display the EU DCC and are available in the respective country: https://ec.europa.eu/info/live-work-travel-eu/coronavirus-response/safe-covid-19-vaccines-europeans/eu-digital-covid-certificate_en. For non-EU citizens without access to the EU DCC certificate, the following exception applies: Click here for all information.