| AppVerk Sp. z o.o. | |
| Appvinio | |
| AppWorks Software | |
| APR System | Świętokrzyskie |
| Aptus.pl | Silesian |
| Apzumi | Greater Poland |
| Arahub Sp. z o.o. | |
| ARC Consulting | |
| ARC Software | |
| Arcabit Sp. z o.o. | Masovian |
| ARCUS S.A. | Masovian |
| Arcus Systemy Informatyczne Sp. z o.o. | Lublin |
| Aret | Greater Poland |
| Arkacom | Masovian |
| Arkency | |
| Arkonsoft | |
| Arscom Usługi Informatyczne | Silesian |
| Art Games Studio S.A. | |
| Art-Com Sp. z o.o. | Silesian |
| ArtCluster Coworking Space | |
| Artech | Masovian |
| ArTeCOM | West Pomeranian |
| Artefakt Sp. z o.o. Sp. k. | |
| Artegence Sp. z o.o. | Masovian |
| Artkai | |
| Artkom | Lublin |
| Artneo | Warmian-Masurian |
| Artnet Sp. z o.o. | Pomeranian |
| Artnova | Masovian |
| ArtP Capital S.A. | |
| Artscape | Silesian |
| ARTSO Agencja Reklamowa | Greater Poland |
| AS Inbank Spółka Akcyjna Oddział w Polsce | |
| Asagao Sp. z o.o. | |
| ASARI | Masovian |
| Ascen | Masovian |
| Asenti | Łódź |
| Askom Sp. z o.o. | Silesian |
| Aspect Finance Sp. z o.o. | |
| AspNetMvc.pl | |
| Asseco Business Solutions | Lublin |
| Asseco Data Systems | Pomeranian |
| Asseco Poland S.A. | |
| ASTE Sp. z o.o. | Pomeranian |
| ASTEC Sp. z o.o. | Lubusz |
| AT Comp | Greater Poland |
| AT Control System | Pomeranian |
| Atcomt | Masovian |
| Atel Electronics | Opole |
| ATERO | Lower Silesian |