| a.p.medien GmbH | Baden-Württemberg |
| A.R. BAYER DSP Systeme GmbH | North Rhine-Westphalia |
| A.T.i. Software GmbH | Bavaria |
| A/C/T Beratungs & System GmbH | Bavaria |
| A1 Professional Software GmbH | Bremen |
| A2C Software AG | North Rhine-Westphalia |
| A2D3 | Bavaria |
| a4 - Computer und Informationssysteme | Saxony-Anhalt |
| a4kom e.K. | Hesse |
| A4VR GmbH | |
| A7soft | Bavaria |
| AAA Computer + Electronic GmbH | Baden-Württemberg |
| AAAHosting GmbH | Baden-Württemberg |
| AABBOO GmbH | Hesse |
| AAC Kabelbearbeitungssysteme GmbH | North Rhine-Westphalia |
| Aachener Bank eG | |
| Aachener Linux User Group | North Rhine-Westphalia |
| Aagon Consulting GmbH | North Rhine-Westphalia |
| aam it GmbH | |
| Aampere GmbH | |
| aap Implantate AG | |
| Aareal Bank AG | Hesse |
| Aareal First Financial Solutions AG | |
| Aareon AG | Rhineland-Palatinate |
| aaris c² | |
| Aaron GmbH | |
| AAronia AG | Rhineland-Palatinate |
| AaviGen GmbH | |
| AAZZUR Services GmbH | |
| AB Agentur Berlin | Berlin |
| AB-DATA GmbH & Co. KG | North Rhine-Westphalia |
| AB-Soft GmbH | Bavaria |
| ABACOM Datensysteme GmbH | Lower Saxony |
| ABACOM Ingenieurbüro GbR | Lower Saxony |
| Abacus Digital GmbH | |
| Abacus Software | North Rhine-Westphalia |
| ABAKUS Internet Marketing GmbH | Lower Saxony |
| abakus it AG | Baden-Württemberg |
| abakus-IT SmartCyber GmbH | Hamburg |
| Abalos Therapeutics GmbH | |
| Abanion GmbH | Baden-Württemberg |
| Abas System GmbH | Berlin |
| Abby | |
| ABC GmbH | North Rhine-Westphalia |
| ABC-System GmbH | Hesse |
| abcbank GmbH | |
| ABCDATA – Thomas Fritsch & Khaled Ben Abed GbR | North Rhine-Westphalia |
| abcfinlab GmbH | |
| Abego Software | North Rhine-Westphalia |
| Abel - Software für Bauingenieure | Baden-Württemberg |