| Synchrotron SOLEIL | |
| Syncly | |
| Syncrosome | |
| Syndicat des Éditeurs de Logiciels de Loisirs | Paris |
| Syndicat National du Jeu Vidéo | Paris |
| Syndivia | |
| Synectique | Nord |
| Synelience Group | |
| Synergee | Hauts-de-Seine |
| Synergica | Territoire de Belfort |
| Synergie Cad | Alpes-Maritimes |
| Synergie Com 360° | Pas-de-Calais |
| Synergie Est | Doubs |
| Synergiss | Paris |
| Synergy Engineering Concept S.A.S. | Bas-Rhin |
| Synertrade | Hauts-de-Seine |
| Synesis | Isère |
| Synexie | Var |
| SynHelix | |
| Synolia | Métropole de Lyon |
| Synoméga | Val-de-Marne |
| Synomia | Hauts-de-Seine |
| Synox | Hérault |
| Syntony GNSS | |
| Sypro | Var |
| Syrade | Gironde |
| Syroco | |
| Syscom Électronique | Essonne |
| SysDream | Hauts-de-Seine |
| SYSEMO | Gers |
| SYSNAV | |
| SysperTec Group | Hauts-de-Seine |
| SYSRA | Essonne |
| Systancia | |
| Systech | Eure-et-Loir |
| Systel Électronique | |
| System Paie | |
| System Plus Consulting | |
| Systemathics S.A.S. | |
| Systematic Paris Région | |
| Systèmes Solaires | Puy-de-Dôme |
| Systemlog | Hérault |
| Systems and Technology International | Val-de-Marne |
| SystemSolutions | Moselle |
| SystemStatus | |
| Systemx | Hauts-de-Seine |
| Systonic | Gironde |
| Systran | Paris |
| Sysun Group | Seine-Maritime |
| Syxperiane | Loire-Atlantique |