- Jacobs University = Constructor University [Bremen]
- James Cook University
- Japan Advanced Institute of Science and Technology
- Japan Atomic Energy Agency
- Japan Institute of Labour
- Japan Victor Company (.)
- jaypee Institute of Information Technology
- Jaypee University of Information Technology
- JCP-Consult
- JD AI Research and Platform
- JE2358
- JE2424
- Jean-Michel Salaun
- JéOcéan
- Jindal Global University
- Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University
- Johann Heinrich von Thünen Institut
- John Paul II Catholic University of Lublin
- John’s Hopkins Berman Institute of Bioethics
- Johns Hopkins University
- Joint Institute for Nuclear Research
- Joint Institute for VLBI in Europe
- Joint Research Centre of the European Commission
- Joint Research Team Pastoralism & Drylands
- Jonction
- JONCTION
- Jouffray-Drillaud
- Journaliste
- Jozef Stefan Institute [Ljubljana]
- J-Pal Europe
- JP Energie Environnement
- Julius Kühn-Institut - Federal Research Centre for Cultivated Plants
- Julius Kühn Institut - Institut für Pflanzenschutz in Obst und Weinbau
- Julius-Maximilians-Universität Würzburg
- JUNIA
- Juniper Networks
- Just One Giant Lab
- Justus-Liebig-Universität Gießen = Justus Liebig University