| Abwasserwerk Vordereifel Westerburg | — | — | Westerburg | Germany |
| AccorHotels | — | — | Issy-les-Moulineaux | France |
| Accumulata | — | +49 89 1780350 | München | Germany |
| Accure | — | — | — | |
| Achim Birr und Guido Wimmer Marketing & Ingenieurberatung GbR | — | — | Aachen | Germany |
| Achim Lohner GmbH | — | — | Polch | Germany |
| Acito Logistics & Kleyling Immobilien GmbH | — | — | Efringen-Kirchen | Germany |
| AckerKapital GmbH | — | — | Münster | Germany |
| Addedval.io | — | — | Berlin | Germany |
| Adenso | — | — | — | |
| Adinco B.V. | — | +31 345 596 000 | NZ Geldermalsen | Netherlands |
| Adolf Hast GmbH & Co. KG | — | — | Heinsberg | Germany |
| Adolf Würth GmbH & Co. KG | info@wuerth.com | — | KÜNZELSAU-GAISBACH | Germany |
| Adolff Beratung und Vermietung | — | — | — | |
| Aerocompact | — | — | Satteins | |
| Aerzener Maschinenfabrik GmbH | — | — | Aerzen | Germany |
| Afilias | — | 353 1 854 1100 | Dublin 1 | Ireland |
| Agco Hohenmölsen GmbH | — | — | Hohenmölsen | Germany |
| AggerEnergie GmbH | — | — | Gummersbach | Germany |
| AggerService GmbH | — | — | Gummersbach | Germany |
| Agorando Technologies GmbH | — | — | Rötha | Germany |
| Agrarhof Menninger GbR | — | — | Hollstadt | |
| Ahg-Gruppe | — | — | Horb am Neckar | |
| AirColleg Göbel eGbR | — | — | Braunfels-Altenkirchen | Germany |
| Airtec Ingenieurgesellschaft mbH | — | — | Köln | Germany |