| D-Link South Africa | Gauteng |
| D3signs Creative Studio | Western Cape |
| DAC Systems | Gauteng |
| Damion-Lee Caldicott | Western Cape |
| DanzLive | |
| Data Video Communications (Pty) Ltd | Gauteng |
| Data World | KwaZulu-Natal |
| Data-Shack | |
| Databias | Western Cape |
| Datacentrix Holdings Ltd | Gauteng |
| Datacraft Software | Gauteng |
| DataDetect | Gauteng |
| Datafin | Western Cape |
| Datakey Group | Western Cape |
| Dataprophet | Western Cape |
| DataRecover | Gauteng |
| Datasmith | Western Cape |
| Datasp | Gauteng |
| DataSwift Software | Western Cape |
| Datatex Dynamics | Western Cape |
| Dataweek | Gauteng |
| dataX | Western Cape |
| David Digital IT Solutions | Mpumalanga |
| Dax Data | Western Cape |
| DC Media S.A. (Pty) Ltd | Gauteng |
| DC3 Distribution | Western Cape |
| DcData | KwaZulu-Natal |
| DCHost Pty Ltd | Gauteng |
| DeARX Services | Gauteng |
| Deck Computer Services | Western Cape |
| Deep Blue | Gauteng |
| Deep Current | KwaZulu-Natal |
| Defcon5 Electronic Services | Gauteng |
| DefenceWeb | Gauteng |
| Definite Web Hosting (Pty) Ltd | Gauteng |
| Deltalink Consulting | Gauteng |
| Delter | Gauteng |
| Department of Communications, Republic of South Africa | Gauteng |
| Department of Telecommunications & Postal Services | Gauteng |
| Design Connection | Western Cape |
| Design from Cape Town | |
| Design Guru | Western Cape |
| Design Media | |
| Design Odyssey | |
| Designs by J9 | |
| Desktop Group | Gauteng |
| DesSoft | Gauteng |
| DETA IT Business | Gauteng |
| Dev InfoTec (Pty) Ltd | Gauteng |
| Dev9 | Gauteng |