The OAI-PMH validation service was discontinued 2025-07-18 and consequently this list of related repositories based on the Implementation Guidelines for the Open Archives Initiative Protocol for Metadata Harvesting - XML Schema for repositories to list confederate repositories is also discontinued.
A static dump of the data from 2025-10-08 is available at https://www.openarchives.org/pmh/registry/ListFriends_HISTORICAL_2025-10-08.xml.