| Cubus-Software España, S.L. | Balearic Islands |
| Cuiner | Balearic Islands |
| Cumesoft | Girona |
| Curapath | Valencia |
| CustomerHunt | Barcelona |
| Cuviv Business Services, S.L. | Barcelona |
| Cxiome España, S.A. | Madrid |
| Cyberclick Agent, S.L. | Madrid |
| Cyberdrive Informática, S.L. | |
| CYC Consultoria y Comunicaciones SI, S.L. | Navarre |
| Cylcom, S.L. | Burgos |
| CYPE Ingenieros, S.A. | Alicante |
| Cytes Biotechnologies, S.L. | Barcelona |
| Cytognos, S.L. | Salamanca |
| Dachs-Kondel | Barcelona |
| Daclub Creatius | Valencia |
| Dagarweb | Murcia |
| Damitel Networks, S.L.U. | Madrid |
| Danysoft International | Madrid |
| Dare Planet Technology | Madrid |
| Dares Technology, S.L. | Barcelona |
| DAS Photonics | Valencia |
| Data Keeper, S.L. | Pontevedra |
| Data-1 Recuperación de Datos | Madrid |
| Data-Bytes Software, S.L. | Murcia |
| Dataclick.es | Alicante |
| Datacom Soluciones Internet Burgos, S.L. | Burgos |
| Datacom.es | Madrid |
| Datacontrol | Málaga |
| Datacyl | Valladolid |
| Datadec | Valencia |
| Dataintro Software | Madrid |
| DATAlife | A Coruña |
| Dataprius, S.L. | Málaga |
| Datarec | Madrid |
| DataRecover | Madrid |
| Datarent | Madrid |
| Dataria | Zaragoza |
| DataSGI | Madrid |
| dataSource S.T.A., S.L.U. | Madrid |
| Datatons | Madrid |
| Datavision | Barcelona |
| Datavoice, S.A. | Madrid |
| DATAX | Barcelona |
| DataZenter | Madrid |
| Datos Masego, S.L. | Madrid |
| Datos.gob.es | Madrid |
| Datosexpress | Barcelona |
| Datosperdidos.com | Madrid |
| DAU Apps | Barcelona |