| Comel d.o.o. | Karlovac |
| Comminus | |
| 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 | |
| Continium Labs d.o.o. | |
| 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 |
| CROads | |
| Croatel d.o.o. | |
| 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 | |
| Croator Web Studio | |
| Crohoster | City of Zagreb |
| Cron d.o.o. | |
| CROZ d.o.o. | City of Zagreb |
| CS Computer Systems | City of Zagreb |
| CSS Weekly | |
| CTIM d.o.o. | Međimurje |
| CTS d.o.o. | Primorje-Gorski Kotar |
| Curious Cat Ltd | |
| Curly Code | |
| CV Sistemi d.o.o. | Zadar |
| cWebSpace d.o.o. | |
| cWebSpace Ltd | Međimurje |
| D4Web | |
| DA-DA Tehnika d.o.o. | |
| dalmaSoft d.o.o. | |
| DaM media | Koprivnica-Križevci |
| Damir Tubak | City of Zagreb |
| DATArius | |
| DataSector | |
| DB Info | |
| De Pol Trade d.o.o. | |
| Debug IT | City of Zagreb |
| Deck99 Ltd | |