| ActiveVB e.V. | North Rhine-Westphalia |
| Activeweb | Lower Saxony |
| activeWeb GmbH | Hesse |
| Activmedia.org | Bavaria |
| Activo GmbH | |
| Actiworks Application Solutions GmbH | Bavaria |
| Acton Capital | |
| Acton Capital Partners GmbH | Bavaria |
| actTHweb | Lower Saxony |
| Actualize | Hesse |
| AcWeDeS | North Rhine-Westphalia |
| Acxiom Deutschland GmbH | Bavaria |
| Acxit Capital Holding GmbH | |
| AD HOK Communication GmbH | |
| AD IT Systems GmbH | |
| ad pepper media GmbH | Bavaria |
| Ad Union GmbH & Co. KG | |
| ad!vantage Agentur für Strategie und Kommunikation | Baden-Württemberg |
| ad-artists GmbH | Hesse |
| Ada Health GmbH | |
| Adalo e.K. | Hamburg |
| Adam die Ahnenverwaltung | Baden-Württemberg |
| Adama GmbH | Hesse |
| adamicus GmbH | Bavaria |
| ADAPT Elektronik GmbH | Bavaria |
| Adasys GmbH | |
| Adata Software GmbH | Lower Saxony |
| Adbex GmbH | Lower Saxony |
| Adbites GmbH | |
| Adblock Plus | North Rhine-Westphalia |
| Adblue Financial Systems GmbH | Berlin |
| ADC Consulting GmbH | Brandenburg |
| adcologne GmbH | North Rhine-Westphalia |
| adcon Gesellschaft für EDV-Dienstleistungen/Beratung mbH | |
| Add Research e.K. | |
| add.min content management | Baden-Württemberg |
| Addag GmbH | North Rhine-Westphalia |
| AddApptr GmbH | |
| ADDI-DATA GmbH | Baden-Württemberg |
| Addi-Data GmbH | |
| ADDITIVE Soft- und Hardware für Technik und Wissenschaft GmbH | Hesse |
| Additive Works GmbH | Bremen |
| ADDIX Internet Services GmbH | Schleswig-Holstein |
| AddWare Solutions | Bavaria |
| Adecc-Systemhaus GmbH | Berlin |
| adelmann-solutions | Baden-Württemberg |
| Adenin | Bavaria |
| adeska internet lösungen | Hesse |
| Adesso AG | North Rhine-Westphalia |
| Adesso Mobile Solutions GmbH | |