| Controlnet Web, S.L. | Cádiz |
| Controltech Ingeniería | Valencia |
| Coodex | |
| CoolPDF Software, Inc. | Balearic Islands |
| Coopdevs | Barcelona |
| Copermática, S.L. | Ciudad Real |
| Copernico Technology | Valencia |
| Coprava | Madrid |
| Coque Informática, S.L. | Madrid |
| Corbax | Murcia |
| Cordero y Asociados, S.L. | Madrid |
| Corebit Sistemas | Madrid |
| Coremain | A Coruña |
| CoreSystems | Madrid |
| Corporación RINDER, S.L. | Biscay |
| Correcto | |
| Correos Telecom, S.A. | Madrid |
| COS Global Services | Madrid |
| COSEOM | Barcelona |
| Cosevi | Sevilla |
| Cosin Consulting | Zaragoza |
| Cosmasoft, S.L. | Madrid |
| Cosmomedia | Valladolid |
| Councilbox | Pontevedra |
| Countermatic | Madrid |
| Coverfy Insurance Services, Correduría de Seguros, S.L. | Barcelona |
| CoverManager | Sevilla |
| Cowocat | Barcelona |
| CPC Servicios Informaticos, S.L. | Madrid |
| Crea tu Sitio Web | Tarragona |
| Creaciones Metrópoli, S.L.L. | Albacete |
| Creaciones Web | Toledo |
| Creacions A la Carta, S.L. | Tarragona |
| Creadtibe Soluciones Tecnológicas, S.L. | Madrid |
| Creaktiva | Cádiz |
| Crealogica.com | Barcelona |
| Crearte | Madrid |
| Createch360 | Barcelona |
| CreativiTIC | Biscay |
| CreativiTIC | Biscay |
| CREC Coworking | Barcelona |
| Creoideas Diseño Web | Badajoz |
| Critic, S.L. | Tarragona |
| Cronoshare | Valencia |
| Crue Universidades Españolas | Madrid |
| CRYO Technology | Madrid |
| CSnet, S.L. | Castellón |
| CTI Electronica, S.L. | Madrid |
| CubeVentures | Madrid |
| Cubitel | Madrid |