| Activa Projectes Informàtics, S.L. | Barcelona |
| Activa Sistemas | Sevilla |
| Active Madrid | Madrid |
| Active servicios informáticos y soporte, S.L.U. | León |
| Active Venture Partners | Barcelona |
| Activiza, S.L. | Pontevedra |
| Actiweb | Barcelona |
| Actúa Comunicación Corporativa | Castellón |
| Actual.cat | Valencia |
| Actualiza tu Negocio SLNE | León |
| Actualweb | Castellón |
| Acuarel | Pontevedra |
| Ad Ventures | Madrid |
| Ad2place | |
| ADA Computer, S.A. | Zaragoza |
| Adaptam Therapeutics | |
| Adapting, S.L. | Valencia |
| Adasoft, S.A. | Barcelona |
| Adatio Sistemas, S.L. | Madrid |
| AdBoosters | Asturias |
| ADC Design Agency | Barcelona |
| Add Value Media | |
| Added Value Solutions | |
| Adding Technology | |
| Addis | Valencia |
| Additio App | Girona |
| Addlink Software Científico, S.L. | Barcelona |
| Adeamatica, S.L. | Biscay |
| adeKi soluciones | Biscay |
| Adema Consultores Medioambientales, S.A. | Madrid |
| Adematica, S.L. | |
| Adequa | Valencia |
| ADI Hardware | Madrid |
| Adil Moujahid | Barcelona |
| Adimedia | Gipuzkoa |
| ADISO Servicios Informáticos | Alicante |
| ADJ Servicos | Murcia |
| ADL Biopharma | |
| ADM Comunicaciones | A Coruña |
| ADmit Therapeutics | |
| Adobe Spain | Barcelona |
| Adoramedia | Alicante |
| AdPime Iberia, S.L. | Barcelona |
| ADR Balears | |
| ADR Infor, S.L. | La Rioja |
| adSalsa | |
| ADSL Zone | Barcelona |
| Adsmurai | Barcelona |
| Adstrakt | |
| Adsystems | Barcelona |