The OCSP responder problem still exists, for all Java 17.0.4+ and 21.0.0+ users. See phase4#124 for technical details. This page now uses CRL instanceof OCSP to work around the issue.

This page lets you check, if a Peppol Participant ID is registered or not. This check is based on querying the DNS and is therefore more reliable then checking the Peppol Directory