- Laadan by Suzette Haden Elgin (110 features)
- Labasje by Max Jeffcott (92 features)
- Laefevesi by Andrej Schütz (89 features)
- Laga by CivilixXXX (54 features)
- Lagu by Maus_Rawr (54 features)
- Laiqbun by Roxy & (97 features)
- Lairats by Becca (1 feature)
- Lajik by Ntena (94 features)
- Lanbuvia by Jacob Manalo (66 features)
- Lang3 by Mountainman (20 features)
- Lántas by Andy Morris (116 features)
- Laozhea by Mia Soderquist (3 features)
- Larler by Zeke Fordsmender (83 features)
- Laroitian by Taylor Selseth (138 features)
- Latadid by Qwynegold (33 features)
- Latejami by Rick Morneau (143 features)
- Latha by Ash (46 features)
- Laucariman by Brv (51 features)
- Lauvinko by Conor Stuart-Roe (108 features)
- Lavrian by Brv (117 features)
- Laytele by Catherine B. Krause (0 features)
- lbana by gibberer (85 features)
- Lci by Amy Klobuchar (18 features)
- LCR by colz (19 features)
- Least Average by JayN (131 features)
- Lekmokulka by Alexander M. Koch (38 features)
- Lembrin by Sander Dieleman (120 features)
- Lemohai by David Johnson (130 features)
- Lemyrian by ali (19 features)
- Leom by mausr (68 features)
- Leopardish III by Xing (49 features)
- Leopardish IV by Xing (33 features)
- Levran by Irkan (143 features)
- Lhaa: Siri by Zach W (62 features)
- Lhenazi by Arthaey Angosii (92 features)
- Lhueslue by Qwynegold (90 features)
- Liberal Diversal by Dean Hyatt (0 features)
- Liberalian by Liberalian Language Authority/Liberalisk Depoto di Langu (33 features)
- lietūska by naghavi, mtl (76 features)
- Lihanian by kina (29 features)
- Limerian by Catherine B. Krause (24 features)
- Lingua Franca Nova by C. George Boeree (116 features)
- Lingwa de Planeta by Dmitrij Ivanov et al. (134 features)
- Linvongo by Andres Rincon (31 features)
- Lioa e Gweu by chridd (15 features)
- LipTalk by Exordia (69 features)
- Literary Fire by reizoukin (25 features)
- Liu by Qwynegold (120 features)
- Livagian [phonetically] by And Rosta (17 features)
- Livagian [phonologically] by And Rosta (128 features)
- Lixaanu hal-'adami by Becca (17 features)
- Llapakhi by Flush (67 features)
- Llapoyan by Solarius (24 features)
- Lodeen by Tètdeupö D'Yaoûrt Pérrimé (35 features)
- Loglan by James Cooke Brown (54 features)
- Lohsee by Jason Benjamin (102 features)
- Lojban by collective, authorsip disputed (119 features)
- Lonaane by Ryan Dell'Erba (29 features)
- Lonmai Luna by k1234567890y (143 features)
- Lortho by Brian Bourque (59 features)
- Lrahran by A Walker Scott (27 features)
- L'starfish Klam by k1234567890y (128 features)
- Luluvo by Valentina Sunazhum (51 features)
- Lup (Simplified) by kryan (141 features)
- Luquv by cromulant (57 features)
- Lwaitel by chridd (114 features)