| Divante | |
| Divstack Sp. z o.o. | |
| Dizply Ltd | |
| Djack Software | Masovian |
| DKK Development | |
| DL Invest Group PM S.A. | |
| DLabs Sp. z o.o. | Pomeranian |
| DLF-Internet | Pomeranian |
| dmt Software House Sp. z o.o. | |
| DNAsoftware.pl | Masovian |
| DNAVI | |
| DO OK | Lower Silesian |
| Dobreprogramy | |
| Dock | |
| Doctor One | |
| Dodowork Sp. z o.o. | |
| DODRUKARKI.PL Sp. z o.o. | Łódź |
| Dogo System | Lubusz |
| DoIT Group Sp. z o.o. | |
| Dolina Lotnicza | |
| Dolsat Sp. z o.o. | Łódź |
| Domainhost.pl | Podlaskie |
| Domainmaker | Kuyavian-Pomeranian |
| DomData AG Sp. z o.o. | Greater Poland |
| Domena | Kuyavian-Pomeranian |
| Domeny.pl | Lesser Poland |
| Domeny.tv | Lower Silesian |
| Domowe Finance PL | West Pomeranian |
| dot n pixel | |
| Dotnetos | |
| DoxyChain | |
| DP Vision Digital Agency | |
| DracoPC | Lubusz |
| Drageus Games S.A. | |
| DreamITeam | Masovian |
| Dreamlike | |
| Drivebox Sp. z o.o. | Lower Silesian |
| Droids On Roids S.A. | |
| Droplabs Sp. z o.o. | |
| Droptica | |
| DrTusz.pl | Podlaskie |
| DRUKARKI Serwis Sprzedaż | Subcarpathian |
| Drukowanie.net | Lower Silesian |
| DrukTalk.pl | Lesser Poland |
| DrupalNinja | |
| Dsecure.me Sp. z o.o. | |
| DSpot Sp. z o.o. | |
| DSR | Lower Silesian |
| DTS Sp. z o.o. Sp.k. | Lesser Poland |
| Dual Core | |