There are 1,585 titles that begin with the letter O
- Open Access Journal of Sports Medicine (EISSN: 1179-1543)
- Open Access Journal of Urology (EISSN: 1179-1551)
- Open Access Macedonian Journal of Medical Sciences (ISSN: 1857-9655)
- Open Access Medical Statistics (ISSN: 2230-3251)
- Open Access Rheumatology: Research and Reviews (ISSN: 1179-156X)
- Open Access Surgery (ISSN: 1178-7082)
- Open Agriculture (EISSN: 2391-9531)
- Open AIDS Journal (EISSN: 1874-6136)
- Open Analytical Chemistry Journal (ISSN: 1874-0650)
- Open Anthropological Research (EISSN: 2657-4233)
- Open Archaeology (ISSN: 2300-6560)
- Open Arts Journal (ISSN: 2050-3679)
- Open Astronomy (EISSN: 2543-6376)
- Open Biochemistry Journal (EISSN: 1874-091X)
- Open Biology (EISSN: 2046-2441)
- The Open biomedical engineering journal (EISSN: 1874-1207)
- Open Cardiovascular Medicine Journal (EISSN: 1874-1924)
- Open Ceramics (EISSN: 2666-5395)
- The Open chemical engineering journal (ISSN: 1874-1231)
- The Open chemical physics journal (ISSN: 1874-4125)
- Open Chemistry (EISSN: 2391-5420)
- The Open Clinical Chemistry Journal (ISSN: 1874-2416)
- Open Computer Science (EISSN: 2299-1093)
- The Open condensed matter physics journal (ISSN: 1874-186X)
- Open Cultural Studies (EISSN: 2451-3474)
- Open Dentistry Journal (EISSN: 1874-2106)
- Open Economics (EISSN: 2451-3458)
- Open Economies Review (ISSN: 0923-7992,EISSN: 1573-708X)
- Open Education Studies (ISSN: 2544-7831)
- Open Engineering (EISSN: 2391-5439)
- Open file report (ISSN: 0149-984X)
- Open Forum Infectious Diseases (ISSN: 2328-8957)
- Open Gender Journal (EISSN: 2512-5192)
- Open Geomechanics (EISSN: 2644-9676)
- Open Geosciences (EISSN: 2391-5447)
- Open Geospatial Data, Software and Standards (EISSN: 2363-7501)
- Open Health (ISSN: 2544-9826)
- Open Health Data (EISSN: 2054-7102)
- The Open Health Services and Policy Journal (ISSN: 1874-9240)
- Open Heart (ISSN: 2398-595X,EISSN: 2053-3624)
- Open Information Science (EISSN: 2451-1781)
- The Open inorganic chemistry journal (ISSN: 1874-0987)
- Open Journal for Legal Studies (EISSN: 2620-0619)
- Open Journal of Astrophysics (EISSN: 2565-6120)
- Open Journal of Bioresources (EISSN: 2056-5542)
- Open Journal of Cardiovascular Surgery (ISSN: 1179-0652)
- Open Journal of Humanities (EISSN: 2612-6966)
- Open journal of implant dentistry (ISSN: 2226-4507)
- Open Journal of Mathematical Analysis (ISSN: 2616-8103,EISSN: 2616-8111)
- Open Journal of Mathematical Optimization (EISSN: 2777-5860)
- Open Journal of Mathematical Sciences (ISSN: 2616-4906,EISSN: 2523-0212)
- Open Journal of Occupational Therapy (ISSN: 2168-6408)
- Open Journal of Psychiatry and Allied Sciences (ISSN: 2394-2053,EISSN: 2394-2061)
- Open Learning (ISSN: 0268-0513,EISSN: 1469-9958)
- Open Library of Humanities (ISSN: 2056-6700)
- Open Life Sciences (EISSN: 2391-5412)
- Open Linguistics (ISSN: 2300-9969)
- The Open Macromolecules Journal (ISSN: 1874-3439)
- Open Material Sciences (EISSN: 2544-7300)
- The Open Materials Science Journal (ISSN: 1874-088X)
- Open Mathematics (EISSN: 2391-5455)
- The Open Medical Informatics Journal (EISSN: 1874-4311)
- Open Medicinal Chemistry Journal (EISSN: 1874-1045)
- Open Medicine (EISSN: 2391-5463)
- Open Medicine (ISSN: 1911-2092)
- The Open Microbiology Journal (EISSN: 1874-2858)
- Open Military Studies (EISSN: 2545-3254)
- Open Mind (EISSN: 2470-2986)
- The Open Mineralogy Journal (ISSN: 1874-4567)
- Open Nanoscience Journal (ISSN: 1874-1401)
- The Open neuroimaging journal (EISSN: 1874-4400)
- The Open Neurology Journal (EISSN: 1874-205X)
- The open nursing journal (EISSN: 1874-4346)
- Open Ophthalmology Journal (ISSN: 1874-3641)
- The Open Organic Chemistry Journal (ISSN: 1874-0952)
- The Open Orthopaedics Journal (EISSN: 1874-3250)
- Open Philosophy (EISSN: 2543-8875)
- The Open physical chemistry journal (ISSN: 1874-0677)
- Open Physics (EISSN: 2391-5471)
- Open Political Science (EISSN: 2543-8042)
- Open Praxis (ISSN: 1369-9997,EISSN: 2304-070X)
- Open Psychology (EISSN: 2543-8883)
- Open Quaternary (EISSN: 2055-298X)
- Open Ranks
- Open research Africa (EISSN: 2752-6925)
- Open Research Europe (EISSN: 2732-5121)
- Open Respiratory Archives (EISSN: 2659-6636)
- Open Respiratory Medicine Journal (EISSN: 1874-3064)
- Open Review of Educational Research (ISSN: 2326-5507)
- Open Rheumatology Journal (EISSN: 1874-3129)
- Open Rivers (ISSN: 2471-190X)
- OPEN ROAD (ISSN: 0048-1947)
- Open Screens (ISSN: 2516-2888)
- Open Shelf (ISSN: 2368-1837)
- Open Sights
- Open Solutions Inc. MarketLine Company Profile
- The Open Source Business Resource (ISSN: 1913-6102)
- Open Source FOR You
- Open Source Jahrbuch
- The Open spectroscopy journal (ISSN: 1874-3838)