| Sunnysoft | Prague |
| Superdesk | |
| Superface | |
| SuperNakup.com | Prague |
| Support System | Hradec Králové |
| SURE.lab | |
| Survio | |
| SVCS Process Innovation, s.r.o. | |
| SVĚT-HUB | |
| SvetHostingu.cz | Moravian-Silesian |
| Svěžíweb.cz | Zlín |
| SWEHQ, s.r.o. | |
| SychrovNET | |
| Syntea software group, a.s. | Prague |
| System Boost, a.s. | |
| System servis, s.r.o. | |
| System4u | |
| SystemOnLine.cz | Prague |
| t-alacarte.com | |
| T-Mobile Czech Republic, a.s. | Prague |
| T-SOFT, a.s. | Prague |
| TA Triumph-Adler Česká republika, s.r.o. | Prague |
| Talentor Advanced Search | Prague |
| Talsec | |
| TaNET West, s.r.o. | Plzeň |
| TAOX, s.r.o. | Zlín |
| TappyTaps, s.r.o. | |
| Taran, s.r.o. | Olomouc |
| Tatra Trucks, a.s. | |
| TC Business School | |
| TC Inter-Informatics, a.s. | |
| TCL Consulting, a.s. | |
| TCL DigiTrade, s.r.o. | |
| TCS net, s.r.o. | |
| TeamOnline, a.s. | Prague |
| TEAS, spol. s r.o. | Zlín |
| Techambition | |
| TechBand, s.r.o. | |
| TechCenter, s.r.o. | |
| Techcentrum, s.r.o. | |
| TechFides Solutions, s.r.o. | South Moravian |
| Techloop | |
| Techmates International, s.r.o. | |
| Techmobil Cheb, s.r.o. | |
| Technická univerzita v Liberci | |
| Technidok, s.r.o. | |
| TECHNISERV IT | |
| Technodat | Zlín |
| TECHNODAT Develop | Zlín |
| Technoline, s.r.o. | |