| Caste it | Split-Dalmatia |
| CEL ART | Istria |
| Chronos Info d.o.o. | |
| Cimerman Software | Međimurje |
| Cinnamon | |
| CITUS d.o.o. | City of Zagreb |
| Claritas d.o.o. | |
| Clover Studio | City of Zagreb |
| Code Of Us d.o.o. | |
| Codel d.o.o. | City of Zagreb |
| Coder d.o.o. | Split-Dalmatia |
| Collective Mind Development d.o.o. | |
| COM 2000 | City of Zagreb |
| Com Eng d.o.o. | City of Zagreb |
| Com Eng Data d.o.o. | |
| Combis d.o.o. | City of Zagreb |
| Comel d.o.o. | Karlovac |
| Compak d.o.o. | |
| Computech d.o.o. | City of Zagreb |
| ComTel Corp d.o.o. | City of Zagreb |
| Conor komunikacije d.o.o. | |
| Conscius d.o.o. | |
| Consensus Nekretnine d.o.o. | |
| Considero d.o.o. | Bjelovar-Bilogora |
| Contego | |
| Control Engineering d.o.o. | |
| Core Media Agency Ltd | Zagreb |
| CoreLine d.o.o. | |
| Corvus Info | City of Zagreb |
| Coting d.o.o. | City of Zagreb |
| Crew803 | City of Zagreb |
| Croadria | City of Zagreb |
| Croatian Artificial Intelligence Association | Zagreb |
| Croatian Hosting | City of Zagreb |
| Croatian Internet eXchange | City of Zagreb |
| Croatian Personal Data Protection Agency | City of Zagreb |
| Croatian Society for Information, Communication and Electronic Technology | Primorje-Gorski Kotar |
| Croatian Web Hosting | |
| Crohoster | City of Zagreb |
| Cron d.o.o. | |
| CROZ d.o.o. | City of Zagreb |
| CS Computer Systems | City of Zagreb |
| CTIM d.o.o. | Međimurje |
| CTS | Primorje-Gorski Kotar |
| CV Sistemi d.o.o. | Zadar |
| cWebSpace Ltd | Međimurje |
| DA-DA Tehnika d.o.o. | |
| DaM media | Koprivnica-Križevci |
| Damir Tubak | City of Zagreb |
| DATArius | |