| ATOS Gruppe GmbH & Co. KG | |
| ATOSS Software AG | |
| ATP Elektronik GmbH | Schleswig-Holstein |
| ATR Industrie-Elektronik GmbH | North Rhine-Westphalia |
| Atral-Secal GmbH | Baden-Württemberg |
| atrify GmbH | |
| Atrios | North Rhine-Westphalia |
| Atriva Therapeutics GmbH | |
| Atron Electronic GmbH | Bavaria |
| Atroplan GmbH | Lower Saxony |
| ATS Elektronik GmbH | Lower Saxony |
| Atspace.com | Schleswig-Holstein |
| Attention Insight | |
| AttractSoft GmbH | Schleswig-Holstein |
| ATV Technologie GmbH | |
| Aucobo GmbH | |
| AuCon GmbH | Bavaria |
| Aucoteam GmbH | Berlin |
| AUCOTEC AG | Lower Saxony |
| Aucta GmbH | |
| AuctionTech | |
| Audatic GmbH | |
| audEERING GmbH | |
| Audibene GmbH | |
| Audicon GmbH | North Rhine-Westphalia |
| Audimex AG | Bavaria |
| Audio Video Elektronik | Thuringia |
| AudioCure Pharma GmbH | |
| Audiodevel | |
| AUDITcapital GmbH | |
| AuditOne GmbH | |
| Auerbach IT | Saxony |
| Aufderheide Webdesign | Lower Saxony |
| Augenklang Webdesign | Saxony |
| AugmentedMind.de | |
| Augmento | |
| August Fichter GmbH | |
| Aurint Software | Mecklenburg-Vorpommern |
| Austerlitz Electronic GmbH | Bavaria |
| AUSY Technologies Germany AG | |
| AutarcTech GmbH | |
| AUTEC Gesellschaft für Automationstechnik mbH | Rhineland-Palatinate |
| Autec GmbH | Saarland |
| Authada GmbH | |
| Authensis AG | Bavaria |
| Authentic Network GmbH | |
| Authoreon.io | |
| authorized.by GmbH | |
| Auticon | |
| AutLay – Automatisches Layout GmbH | |