| Arrow Europe | — | — | Madrid | Spain |
| Arteria | — | +43 699 10509386 | — | Austria |
| Artur Summ GmbH & Co. KG | — | — | Villingen | Germany |
| Asamnet | — | +49 9621 496425 | Amberg | Germany |
| Asdf | — | — | — | Germany |
| Asf | — | — | Mountain View | United States |
| Atelier & Geschenke Jaitner | — | — | Müncheberg | Germany |
| Athos-Ing.-Büro Energieeffizienzberatung | — | — | Eggenstein-Leopoldshafen | Germany |
| Atlantic Labs | — | — | Berlin | |
| Atracco AB | — | — | Hedemora | Sweden |
| AuTop Gliching GmbH | — | — | Gilching | Germany |
| Audi | — | +49 841 890 | Ingolstadt | Germany |
| Auer Metallprofile GmbH | — | +49 3771 28680 | — | Germany |
| Aufbereitung Wolfach | — | — | Wolfach | Germany |
| Aug-E | — | — | — | |
| August Mink GmbH & Co. KG | info@mink-buersten.de | — | Göppingen | Germany |
| Aumer Bioenergie GmbH & Co. KG | — | — | Schorndorf | Germany |
| Auratec | — | — | Aalen | Germany |
| Aurubis AG | — | — | Hamburg | Germany |
| Aurum Solar GmbH & Co. KG | — | — | Hirschberg a. d. Bergstraße | Germany |
| Aurum-Impact | — | — | — | |
| AutenSys | — | — | — | Germany |
| Auto A | — | — | Vohburg a.d.Donau | Germany |
| Auto Center A. Mühlenbruch GmbH | — | — | Neunkirchen | Germany |
| Auto Heidingsfelder | — | — | Merkendorf | Germany |