| Advantic GmbH | Schleswig-Holstein |
| Advantic Systemhaus GmbH | Saxony-Anhalt |
| ADVARIS Informationssysteme GmbH | Baden-Württemberg |
| ADventas Consulting | Hamburg |
| Adventos GmbH | Hamburg |
| advICo mircroelectronics GmbH | North Rhine-Westphalia |
| Adviion GmbH | Baden-Württemberg |
| AdVision digital GmbH | |
| AdvoCoder UG (haftungsbeschränkt) | |
| AEB SE | |
| AED SICAD Aktiengesellschaft | North Rhine-Westphalia |
| Aed-sicad AG | North Rhine-Westphalia |
| aedifion GmbH | |
| AEMtec GmbH | Berlin |
| aenia International GmbH & Co. KG | Baden-Württemberg |
| Aeotec Group GmbH | |
| Aequitas Software GmbH & Co. KG | |
| AERAsec | Bavaria |
| Aerosoft GmbH | North Rhine-Westphalia |
| AeroSys | |
| Aervideo GmbH | |
| Aerzener Maschinenfabrik GmbH | |
| Aesku.Group GmbH | |
| Aeterna Electronic GmbH | Bavaria |
| Aetka Communication Center AG | Saxony |
| aevum GmbH | Bavaria |
| Aextra Software | Lower Saxony |
| AF Data Systems GmbH | |
| AF Inventions GmbH | Lower Saxony |
| AF Unternehmensberatungs- und Beteiligungs GmbH | North Rhine-Westphalia |
| AFAP-AVA | North Rhine-Westphalia |
| afb Application Services AG | Bavaria |
| Affilix Ltd | Lower Saxony |
| Affimed GmbH | |
| AFG Ausführungsgesellschaft für Gebäudetechnik mbH | |
| AFI GmbH | Baden-Württemberg |
| Afp-Technologie | Lower Saxony |
| AFS-Software GmbH & Co. KG | Hesse |
| AFT Microwave GmbH | Baden-Württemberg |
| AFTS GmbH | |
| Agando | Lower Saxony |
| Agenda Informationssysteme GmbH & Co. KG | Bavaria |
| Agendis Business Center Stuttgart | |
| Agens Consulting GmbH | Bavaria |
| Agentes AG | Bavaria |
| Agentscape AG | Berlin |
| Agentur Bonk | Hesse |
| agentur elf42 | Lower Saxony |
| Agentur Karl & Karl | Schleswig-Holstein |
| Agentur sehpunkt, Petzold, Pfäffle & Partner GbR | Baden-Württemberg |