| Data Ireland | |
| Data Protection Commission | |
| Data Protection Commissioner | Dublin City Council |
| Data Rescue | |
| Data Works | |
| Dataconversion Direct Ltd | |
| Dataduct Technologies Ltd | Dún Laoghaire-Rathdown County Council |
| DataDyne Consulting | |
| Datalex | Dublin City Council |
| DataRecovery | South Dublin County Council |
| DataRep | |
| Dataships | |
| DataSolutions Ltd | Dublin City Council |
| Datatrust | South Dublin County Council |
| DataTrust Ltd | Dublin City Council |
| Dataworks Ltd | Waterford City and County Council |
| DB Alliance Ltd | Cork County Council |
| DCB Group Ltd | Wicklow County Council |
| DCU Ryan Academy | Dublin City Council |
| DecaWave | Dublin City Council |
| Deciphex | |
| DEITG | |
| DeJAY Royale | South Dublin County Council |
| Delmec Engineering Ltd | Carlow County Council |
| Delta Partners | Dublin City Council |
| Delta Partners Ltd | |
| Design Tribe | |
| Design Wave | |
| Design Wizard | |
| Designedly | |
| Designit Creative Consultants Ltd | |
| DesignPro Automation | |
| Dev Centre House | Dublin City Council |
| Deveire | |
| Devensis Ltd | |
| Devfair | |
| DeviceAtlas Ltd | |
| DFT Games | |
| DIDWW Ireland Ltd | Dublin City Council |
| DIDWW Ireland Ltd | |
| Digi Wolf | |
| Digico | |
| Digigrow | |
| Digigrow Ltd | Dublin City Council |
| Digiprove Ltd | Fingal County Council |
| Digisat | |
| Digisoft.tv | Cork City Council |
| DIGIT Gaming Studios | Dublin City Council |
| Digital Advantage | |
| Digital Insights | |