| ARATECH | Madrid |
| Arbol Computer | Barcelona |
| Arcadina | Valencia |
| Architechtures | Málaga |
| Archivel Farma, S.L. | Barcelona |
| Arditec Sistemas | Barcelona |
| Arditech Nuevas Tecnologias | Valencia |
| AREA Software Solutions | Barcelona |
| Área Web Creativa | Castellón |
| Area25 | Granada |
| Arena Financial Tech | Madrid |
| Arenet | Madrid |
| Arengu | A Coruña |
| Aresbank | |
| ARG Consulting | Murcia |
| Argilla | Madrid |
| Argus Disseny | Barcelona |
| ARION Grupo | Sevilla |
| Aritmos | Lleida |
| Arkadel 21, S.L. | Madrid |
| Arkadia Space | Castellón |
| Arktec, S.A. | Madrid |
| Arnold & Sellés, S.L. | Madrid |
| Arold Solutions | Madrid |
| Arousa Digital | Pontevedra |
| Arrays for Cell Nanodevices, S.L. | |
| Arroba Capital, S.L. | Barcelona |
| Arsenet Servicios en Internet, S.L. | Madrid |
| Arsys Internet, S.L.U. | La Rioja |
| Art Project Group Developers, S.L. | Málaga |
| Artax Games, S.L. | Madrid |
| Arte | Santa Cruz de Tenerife |
| Arte Digital Producciones | Madrid |
| Arteixo Telecom S.A. | A Coruña |
| Artemedia | Sevilla |
| Arteria Creativa | León |
| Arteria Studios, S.L. | Madrid |
| Arthex Biotech | Valencia |
| Ártica Soluciones Tecnológicas, S.L. | Madrid |
| Artifices.net | Balearic Islands |
| Artificial Intelligence Techniques Ltd | Salamanca |
| Artimedia | Barcelona |
| Artsessions | Barcelona |
| Arume Desenvolvementos Informáticos, S.L. | A Coruña |
| Arwen desarrollo web y diseño | Navarre |
| Aryan Comunicaciones | Madrid |
| AS Computer | A Coruña |
| AS Software | Madrid |
| Asabys Partners | Barcelona |
| Ascendente | Valencia |