| Salu.cz | Prague |
| Samba.ai | |
| Samo Brno | |
| Samo Systems, spol. s r.o. | |
| Santiago Lab | |
| Saperta, s.r.o. | |
| SAPRO, s.r.o. | Moravian-Silesian |
| SATCOM | Prague |
| SATinternet.info, s.r.o. | |
| SatisMeter | |
| Sberbank CZ, a.s. | Prague |
| SCS Software s.r.o. | Prague |
| SE-MO Data | Moravian-Silesian |
| SEA, spol. s r.o. | Prague |
| SEAL Communication, s.r.o. | |
| SearchTeam | |
| SeCons Ltd | Prague |
| SEKO system, s.r.o. | Moravian-Silesian |
| Sendmark.io | Prague |
| SENO, spol. s r.o. | Prague |
| Sense Arena | |
| Sentien HQ, s.r.o. | |
| SEO Expert, a.s. | Prague |
| Servodata, a.s. | Ústí nad Labem |
| Sewio Networks, s.r.o. | |
| seznamzbozi.cz | Prague |
| SH.cz, s.r.o. | Prague |
| Sharry | |
| Shean s.r.o. | South Moravian |
| Shopsys, s.r.o. | Moravian-Silesian |
| Shopsys, s.r.o. | |
| Shoptet, s.r.o. | Prague |
| Showmax Engineering | |
| SICONET, a.s. | |
| Siesta Codes | |
| Siesta Solution, s.r.o. | |
| Sigma Soft, spol. s .r.o. | |
| Signals Network | |
| Simac Technik ČR, a.s. | Prague |
| Simpleway Europe, a.s. | |
| Simplity | |
| Škoda Auto DigiLab, s.r.o. | |
| SkyMaps | |
| Skyvia | |
| Slezská univerzita v Opavě - Matematický ústav v Opavě | Moravian-Silesian |
| Smart Heating Technology, s.r.o. | |
| SMART Office & Companies, s.r.o. | |
| Smart Prague | Prague |
| Smart Technologies, s.r.o. | |
| Smart4Web | |