The Open Harvester Systems is a free metadata indexing system that allowers users to create a searchable index of the metadata from Open Archives Initiative (OAI)-compliant archives, such as sites using Open Journal Systems (OJS) or Open Conference Systems (OCS). It can harvest OAI metadata in a variety of schemas (including unqualified DC, the PKP (Open Journal Systems/Open Conference Systems) Dublin Core extension, MODS, and MARCXML).