| Signarama | |
| Signature S.A.S. | Loire |
| Signitic | |
| Signoret | Alpes-Maritimes |
| SII | Seine-Saint-Denis |
| Siit | |
| Sil'Age | Indre-et-Loire |
| Silae | |
| Silex App | |
| Silicom | Yvelines |
| Silicon Mobility | Alpes-Maritimes |
| Silicon.fr | Hauts-de-Seine |
| Silog | Calvados |
| Silverpeas | Isère |
| Silverprod Group | Métropole de Lyon |
| SimaWay | Nord |
| Simbel | |
| Simcore | Ille-et-Vilaine |
| Simon Web | Aude |
| SimpleLogin S.A.S. | |
| Simplicité Software | |
| Simpliciti | |
| Simplon | Seine-Saint-Denis |
| Simply Move | |
| Simplydesk | Métropole de Lyon |
| SimtelCom | Sarthe |
| SimTrade | |
| Simulassur | |
| Simulation Open Framework Architecture | Bas-Rhin |
| Sinay S.A.S | |
| Sindup | Maine-et-Loire |
| Sine Qua Non | Paris |
| Sinequa | |
| Sinergence | Nord |
| Sinergis | |
| Sinetis | Bouches-du-Rhône |
| Sinfin | |
| Singular Capital Partners | |
| Siparex | |
| Sipartech | Paris |
| SiPearl | |
| Siradel | Ille-et-Vilaine |
| Sirap | Drôme |
| Sirius NeoSight | |
| SIROM | Paris |
| Sirup Lab | |
| Sis ID | |
| SISalp | Var |
| Sismeo | Paris |
| Sismics | |