Jambojet.com,  Nairobi, Kenya, founded 2014 as low fare subsidary of Kenya Airways(q.v.).
 -                             #1,                                                                 #2:

Japan Asia Airways (JAA), Shinagawa, Japan, 1975-2008 merged into JAL.     -  #3:

Japan Air Commuter  (JAC), Kagoshima, Japan, founded 1983.    -   #3:

Japan Airlines (JAL), Shinagawa, Japan, founded 1951:
  -         #32,                       #5,                                  #11,                                   #33:

-                              #2,                             #13J /13D,                                          #24:

  -                      #7,                                   #4,                                       #18/#18J:

  -               # 1,                                # 6,                                  #23/#23a,                   #25:

-                                #27,                                                        #31:

JAS - Japan Air System,  1971-2004, founded 1971 by merger as TOA Domestic, renamed
1988 as JAS, 2004 renamed as Japan Airlines Domestic.    -    #1,     #4,   #3/#7(rear different):
 
JAT - Jugoslovenski Aerotransport, Belgrade, Yugoslavia, 1927-2003:
-            #15(old, 30cm tall bag),                 #3,                                                   #6:

-            #7a,                                           #9,                                                     #1:

JAT Airways, Belgrade, Serbia, founded 2003.     -   #10,                   #14:

Jazeera Airways, Kuwait, founded 2005.     -  #1:

JC Int'l Airlines, Phnom Penh, Cambodia, founded 2014, maiden flight March 2017.   - #1:

JEJU Air, Jeju-City, Korea, founded 2005.
-    #1/#3(diff closure),            #2,        #5(Normal paper, JEJUair in gussets)/#6(glossy, plain gussets):

Jersey European Airways, Exeter, UK,  1979-2000 renamed to British European and 2002 to flyBE.
-                   #3,                                                 #2:

Jetair Caribbean, Willemstad, Curacao - Dutch Antilles, founded 2019.    -    #1:

Jet Airways, Mumbai, India, 1992 - 2019.                -    #7,                    #4:

-     #9/#10/#10a/#13(diff paper, color shade, fold line, clip rear);          #2:

Jet Aviation, Basel, Switzerland, founded 1967.    -   #1:

Jet2.com, Leeds, UK, founded 2002.          - #1:

Jet4you, Casablanca, Morokko, founded 2006.       -  #1,                  #2:

JetBlue Airways, New York, USA, founded 1999.        -    #2:

Jet Lite, Mumbai, India, founded 2007 by renaming from Air Sahara(q.v.), ceased 2019.     -   #2:

JeTran Air, Bucharest, Romania, founded 2005.     -   #1:

Jet Star, Melbourne, Australia, founded 2003.
-                            #2,                 Promotion bag code JS5,                              #3:

-      #6                and                   #7/#8(slimer width):

Jet Star Pacific, Hanoi, Vietnam, founded 2008 by renaming from Pacific Airlines(q.v.)
and renamed back to old name in June 2020.         -  #2:

Jiangxi Air, Nanchang, Jiangxi Prov., China, founded 2014, maiden flight Jan 16.   - #1:

JIN AIR (low fare subsidary of Korean Air), Seoul, Korea, founded 2008.    -   #1:

JMC Airlines, Manchester, UK. Formed 2000 by merger
of FlyingColors and the charter remainings of Britisch Caledonian,
rebranded as Thomas Cook 2003.    -   same design  #1(flat base) /#2(pointed base):

Joy Air, Xi'an, Shaanxi, China, founded 2008.          -   #1:

Juneyao Airlines, Shanghai, China, founded 2005.  
  -      #1,                      #1A,                   #2/#2A(thinner types)/#2B(lighter colors),      #3:

-            #4,                                     #5: