- Sådlensk by Sanna Lys (2 features)
- SAE by Martin Haspelmath (16 features)
- Saftian by MarrisUes (34 features)
- Saimiar by con quesa (92 features)
- Sakalian by King Anorion (8 features)
- Sakawi by k1234567890y (123 features)
- Salga by Hannes (76 features)
- Salhari by Alex Sands (91 features)
- Salthan by Foolster41 (15 features)
- Sambahsa by Dr. Olivier Simon (138 features)
- Sa'nakkan by Ilasir Maroa (71 features)
- Sape by Gufferdk (114 features)
- Saremite, Old by Sectori (135 features)
- Sarian by decem (85 features)
- Sarikan by Chaok (50 features)
- SASXSEK by Dana Nutter (111 features)
- Satang by M. D. (125 features)
- Sathir by David J. Peterson (40 features)
- Sathura by Irkan (45 features)
- Sattashee by Knut F. K. Ulstrup (0 features)
- Savvinic by kanejam (126 features)
- Saya by brandrinn (56 features)
- Sazhir by Strahinja Ćirić (59 features)
- Scotian by Doug Barton (133 features)
- Scrowdian by Xavier Haag (4 features)
- Seignuric by Hendrie Corbie (59 features)
- Seiyotogo by Unknown (14 features)
- Selade by Peter Cannici (99 features)
- Senduri by David Johnson (94 features)
- Sen:esepera by Jeffrey Henning (68 features)
- Senire by Justin M.G. (17 features)
- Senjecas by Charles W. Brickner (134 features)
- Sentalian by Finlay (120 features)
- Sermu by Rebecca Withwi (0 features)
- Sese by Jack Eisenmann (51 features)
- Seto ka'palo by k1234567890y (116 features)
- Settamu by Fimi (98 features)
- Sevzoi by Taraiph (17 features)
- Shalolese by dhagrow (107 features)
- Sheleted by Julanga (0 features)
- Shemspreg by Dirk Elzinga (17 features)
- Shinmavu by Informer (4 features)
- Shinsali by Anatoli Kudrin (1 feature)
- Shokitin by Andrew Nelson (124 features)
- Shsiwhe Luwur by Jakob Colle (141 features)
- Shujum by Brv (47 features)
- Shuran by Hiztegi (49 features)
- Shurs by Bryony (70 features)
- SIAL by Jeffrey S. Jones (118 features)
- Si'asigu by Michael Caffery (99 features)
- Siaswo by M (121 features)
- Sibirgo by Salmon the King (140 features)
- Sieptsechaung by wycerum (1 feature)
- Siginese by Ali Ghozali (19 features)
- Sihaku by Benjamin Schwantner (48 features)
- Simbri by Lande (140 features)
- Simpified japanese by Alexander Frankland (30 features)
- Sindarin by J. R. R. Tolkien (120 features)
- Sirgyr by Bryony (92 features)
- Sjal by Erik (138 features)
- Skerre by Doug Ball (94 features)
- Slavk by samstyan99 (0 features)
- SLMN by colz (19 features)
- Slyrdian by Felix Sieber (105 features)
- Snahhian by IlL (143 features)
- Sngõlpowhetet by Josh Regev (38 features)
- Soc'ul' by Dillon Hartwig (143 features)
- Solaric by Taylor Selseth (141 features)
- solresol by François Sudre (44 features)
- Somaltepota by shirkamisamyogai (11 features)
- Somish by Aaron Chapman (94 features)
- Sona by Kenneth Searight (141 features)
- Sonerha by nijukona (45 features)
- Song by triskara (19 features)
- Songulda by Qwynegold (61 features)
- Sonorian by Me (Brádán Nomini) (69 features)
- Sonsear by Coretteket (18 features)
- South Eresian by Risla (118 features)
- South Germanic by Hannes (67 features)
- South Picksalladed by Ember Nickel (59 features)
- Spanglo by Me (25 features)
- Speech of the New West by almaril (43 features)
- Spraka by W (140 features)
- Sqopran by DeerLad (82 features)
- Sreasra Mdatla by Alexander M. Koch (7 features)
- Standard Ancaron by Lyhoko Leaci (118 features)
- Standard Hymmnos by Akira Tsuchiya (86 features)
- Standard Knrawi by Dillon Hartwig (143 features)
- Stemmutsian by James Seamus (66 features)
- Sudyrnish by Dillon Hartwig (143 features)
- Suhon by Xing (39 features)
- Suiacuili by chridd (118 features)
- Summerlandic by Rebecca Ashling (44 features)
- Sunbyaku by Chagen (130 features)
- Sǔra by Jaime Wolfe (79 features)
- Surang Jumbar by Qwynegold (100 features)
- Surimban by colz (14 features)
- Surnichian by Agricola Avicula (16 features)
- Svørgska by Kyle Carnahan (83 features)
- Sylvan by Enrique Gamez (108 features)
- Syt by kalathei95 (116 features)
- Szezk by B (111 features)