| AB Internet | Madrid |
| Abac Capital | Barcelona |
| Ábaco Software | Barcelona |
| Abacus Telecom | |
| Abaestudio | Madrid |
| Abakan Sistemas de Información, S.L. | Almería |
| Àbakos | Barcelona |
| Abalia | Madrid |
| Abalit Technologies | Barcelona |
| ABAMobile Solutions, S.L. | |
| Abansys | Valencia |
| Abanzamed | |
| Abast | Barcelona |
| ABC-Creación Digital | Valencia |
| Abertal Networks, S.L. | A Coruña |
| Abetelnet Solutions | Madrid |
| ABF Interactiva | Madrid |
| Ability Pharma | |
| Abity Comunicación Multimedia, S.L. | Barcelona |
| Able Human Motion, S.L. | Barcelona |
| ABP Tecnologica | |
| äbranding | Valencia |
| Abreink | |
| Abroaden Holdings Ltd | Barcelona |
| ABRSoft | Huesca |
| AC Camerfirma, S.A. | Madrid |
| Accelya Holding World, S.L. | Barcelona |
| Accesocero | Madrid |
| Accesorios y Telecomunicaciones Famz, S.L. | Málaga |
| Accesos y Comunicaciones del Sur, S.L.L | Almería |
| Access Basic Server, S.L. | Alicante |
| Acciona | |
| ACCIONA Energy | |
| Accon Software | Barcelona |
| Accure Therepeutics | Barcelona |
| Acens Technologies, S.L.U. | Madrid |
| Acerca | Barcelona |
| Acernet | Valencia |
| Acid Tango, S.L. | |
| ACIGRUP Hospitality Software | Tarragona |
| Acilia | Madrid |
| Acknowledgment, S.A.L. | Zaragoza |
| ACKstorm | |
| Acompany | Barcelona |
| Acomsis Solutions, S.L. | Madrid |
| Acorde Technologies | |
| ACR Comunicación | A Coruña |
| ACTIONS | Madrid |
| Actiserver Advertising | Barcelona |
| Activa Control | Barcelona |