- Ianqaeni by Fenhl (0 features)
- Iaskyon by Kenneth Ngan (43 features)
- Iathi by J. Thomas Crisler (63 features)
- Icnac by Josh Regev (36 features)
- ideolat (ideographic latin) by storpidul (1 feature)
- Idhunaic by Irkan (92 features)
- Idiom Neutral by Akademi Internasional de Lingu Universal (18 features)
- Ido by Louis de Beaufront, Louis Couturat (143 features)
- Ieteje by Solarius (89 features)
- iigraa by worldofcrazies (137 features)
- Ilaini by Irina Rempt (106 features)
- Ilawokou by Simon Nordman (22 features)
- Ilcharotic by V. Esp (130 features)
- Iliatarian (Lerewe Giri) by Michael M. Goessler (52 features)
- Iliatarian (Sulutmuri & Ngwano) by Michael M. Goessler (51 features)
- Illicraic by V. Espinosa (126 features)
- Iloyan by Kierán Meinhardt (103 features)
- Ilvarii by Ilasir Maroa (23 features)
- Imuthan by Kári Emil Helgason (133 features)
- Inan by Becca (1 feature)
- inapo-sakai by Hayate (139 features)
- Indertonne by Mark H. Betternage (110 features)
- Infernal by Enrique Gamez (78 features)
- Inilt by Serafín (141 features)
- Inote by Sectori (123 features)
- INS by yochema95 (143 features)
- Insular Kett by Nortaneous (29 features)
- Intal by Erich Weferling (118 features)
- Interesting by Kiriyow (45 features)
- Interglossa by multiple authors (51 features)
- Interlingua by International Auxiliary Language Association (85 features)
- Interlingua Antic by Becca (99 features)
- Interlingua Romanica by Academia Pro Lingua Romanica (0 features)
- Interlingue (Occidental) by Edgar de Wahl (115 features)
- Interslavic by Juraj Križanić (74 features)
- Ipiki by Xing (69 features)
- Iqglic by Jack Eisenmann (111 features)
- Irani by eerD (145 features)
- Iridian by A Walker Scott (10 features)
- Ishtol by Berek (123 features)
- Isitya by Syoci (37 features)
- Islysian by Cody Jaeger (76 features)
- Isolating thing inspired by mesoamerican and southeast asian by colz (139 features)
- Isoldian by Gintamil (102 features)
- Isthmian Daaci by makhnoboi19 (7 features)
- Istokahi by Háček (118 features)
- Isuhuwum by Piotr Gepfert (79 features)
- Ithkuil III by John Quijada (137 features)
- Itra Kir by shumai (102 features)
- Ixe Wa by cromulant (112 features)