- Dacayan by Ali Ghozali (143 features)
- Dahawj by Flush (53 features)
- Dahilese by Taylor Selseth (132 features)
- Dahu by David Johnson (135 features)
- Dainyu by penguinsquishy (43 features)
- Daisilingo by Jian Huang (107 features)
- Damin by people of the Lardil and the Yangkaal tribes (15 features)
- Damiyaa by Aszlan (67 features)
- Dangin Nira by Michael McClellan (43 features)
- Dapaq by Udrihel (21 features)
- Darsra by Chase Agheli (6 features)
- Dearean by Lochethmi (78 features)
- Deata by Loren Bowman III (13 features)
- Deiku by RagTagBunch (23 features)
- Deinau by xroox (57 features)
- Deini by Dana Nutter (43 features)
- Delang by Koppa Dasao (57 features)
- Deleted Language by Veoler (0 features)
- Delete this by Delete this (2 features)
- Delniit by Zarainia (143 features)
- Denaden by Fa Jusifus (91 features)
- Depth Language by ol bofosh (6 features)
- Derovian by Kierán Meinhardt (95 features)
- Dètren by Udrihel (58 features)
- Dhakhsh by Brian Bourque (30 features)
- Dhannuá by Caudimordax (70 features)
- Dharratta by Far (10 features)
- Dheneydabus by marvelousbecca (49 features)
- Dhrahhynian by Fluffy8x (== Uruwi) (140 features)
- Diplomatic Shessith by WhimsicalXellos (15 features)
- diSellat by leanancailin (103 features)
- Diversal by Dean Hyatt (0 features)
- Dladwu by Bryony (51 features)
- Doayâu by Jan Strasser (104 features)
- Doline by Diana R. (32 features)
- donawean by maadio (90 features)
- Dothraki by David J. Peterson (103 features)
- Doubleyew Eyepea by Brv (68 features)
- Draconic by WhimsicalXellos (141 features)
- draga by Ajinkwai (80 features)
- Dragonian by Solthree (48 features)
- Dravean by Deiniol Jones (140 features)
- Duemál by Jan Olisiejko (23 features)
- Dunia by Ed Robertson (136 features)
- Dutton Speedwords by collective, Reginald J. G. Dutton (0 features)
- Dwarvish by Maus_Rawr (67 features)
- Dwendish by Rebecca Ashling (66 features)
- Dzidmitsu by Aomi (27 features)
- Dzuutani by Flush (80 features)