- Jacobs University = Constructor University [Bremen]
- Jagiello'nski
- Jahangirnagar University
- Jakarta Islamic State University
- Jan Dlugosz University in Czestochowa
- Japan Advanced Institute of Science and Technology
- Japan Aerospace Exploration Agency [Sagamihara]
- Japan Agency for Marine-Earth Science and Technology
- Japan Atomic Energy Agency
- Japan Atomic Energy Agency [Ibaraki]
- Japanese French Laboratory for Informatics
- Japan Meteorological Agency
- Japan Science and Technology Agency
- Japan Synchrotron Radiation Research Institute [Hyogo]
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Jazan University
- Jean-Marie Mariotti Center
- Jena University Hospital [Jena]
- Jenderal Soedirman University
- Jenner Institute [Oxford]
- Jenoptik, ESW GmbH, Teltow, Germany
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy [Preston]
- Jerzy Haber Institute of Catalysis and Surface Chemistry
- Jet Propulsion Laboratory
- Jeunes Équipes de l'Institut de Physique du Collège de France
- J. Heyrovský Institute of Physical Chemistry of the ASCR
- JiangNan University
- Jiangsu Normal University
- JiangSu University
- Jiangsu University of Science and Technology
- Jichi Medical University [Tochigi-Ken, Japan]
- Jilin University
- Jinzhong University
- Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University
- Johns Hopkins Bloomberg School of Public Health [Baltimore]
- Johns Hopkins University
- Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
- Johns Hopkins University School of Medicine [Baltimore]
- Joint Center for Structural Genomics
- Joint Institute for the Study of the Atmosphere and Ocean
- Joint Laboratory for Petascale Computing [Illinois]
- Joint Research Centre
- Jomi Leman SA
- Joseph Louis LAGRANGE
- Jozef Stefan Institute [Ljubljana]
- JRC Institute for Environment and Sustainability
- JRC Institute for Health and Consumer Protection
- JST
- JST-CREST
- Jülich Supercomputing Centre
- Jülich Supercomputing Centre Forschungszentrum Jülich GmbH Jülich, Germany
- Jülich Supercomputing Centre, Institute for Advanced Simulation
- Julius Centre for Health Sciences and Primary Care
- Julius-Maximilians-Universität Würzburg = University of Würzburg
- JUNIA
- Justus-Liebig-Universität Gießen = Justus Liebig University