| Iterait, a.s. | |
| ITPro CZ | Pardubice |
| J&T Banka | Prague |
| J&T Banka, a.s. | |
| J&T Ventures | Prague |
| Jan Bien | Prague |
| Jan Pivoňka | Prague |
| Jan Polzer | |
| JenaSoft | Prague |
| JetBrains, s.r.o. | Prague |
| JetSoft, s.r.o. | Prague |
| JettyVision, s.r.o. | Prague |
| Ježek software, s.r.o. | Liberec |
| JIC | South Moravian |
| Jihočeská univerzita v Českých Budějovicích | |
| JIMAZ, s.r.o. | Prague |
| Jiří Ježek | Liberec |
| JIRRA Software, s.r.o. | Pardubice |
| JK Education, s.r.o. | |
| JM-Net z.s. | Prague |
| Josef Stříbný | South Moravian |
| JPM Technologies, s.r.o. | |
| JRX automation, s.r.o. | |
| JS a partner, s.r.o. | |
| JSJT Automation, s.r.o. | |
| Juicymo, s.r.o. | Prague |
| JVM Computers, spol. s r.o. | Prague |
| JWA Prague, s.r.o. | |
| K-system.CZ, s.r.o. | |
| Kabelmánie, s.r.o. | South Moravian |
| Kancelář CATO, s.r.o. | |
| Kancelářské systémy, a.s. | |
| KARAT Software a.s. | Olomouc |
| Karsa Technologies, s.r.o. | Hradec Králové |
| KAST, spol. s r.o. | Prague |
| KASTNER software, s.r.o. | Olomouc |
| Katedra informatiky FEI VŠB-TUO | Moravian-Silesian |
| Kaya | |
| KCT Data | |
| Keboola | |
| Keen Software House, s.r.o. | Prague |
| KELOC CS, s.r.o. | South Moravian |
| Kesh | |
| Kinalisoft, s.r.o. | |
| Kindred Group, s.r.o. | Prague |
| KMB systems, s.r.o. | Liberec |
| KMZ engineering, s.r.o. | |
| KnVnet services, s.r.o. | Central Bohemian |
| KOALA42 | Prague |
| KOMETA Plzeň, s.r.o. | |