So-called “mirror journals” are Open Access offshoots of already existing Closed Access journals, with similar names and identical subjects, and thus represent a form of hybrid journals. Articles in „mirror journals“ are therefore not eligible for funding, even if the journals are listed in the DOAJ.
For the exact definition of "mirror journals", see the DOAJ "Guide to applying" page.
In a joint work group, composed of staff from the university libraries of TU Berlin and TU Braunschweig, as well as from the Charité and Forschungszentrum Jülich (Research Center Jülich), review criteria were developed and a list of "mirror journals" was complied.
The "OA-Zeitschriftenliste DFG-Anträge" (OA journals list DFG applications (DE)) is composed of journals from the DOAJ and the "Bielefelder Liste" ISSN-Gold-OA (Bielefeld list ISSN Gold OA (DE)). "Mirror journals" have been removed. Thus, a comparison with the list can also be helpful in determining if a particular journal is a "mirror journal".
Otherwise, the list is used in the Open Access Monitor web application as a filter for evaluations to support applications for the DFG funding program "Open Access Publication Funding".