| Dataworks S.a.s. | Rome |
| Date Group S.r.l. | Turin |
| Datef AG | South Tyrol |
| Dati.gov.it | Rome |
| DatoCMS | Florence |
| Dauvea S.r.l. | |
| Davide Nanni Web Agency Bologna | Bologna |
| Davidedattoli | Brescia |
| DaVinciFace AI | Florence |
| Day One | Rome |
| DazeTechnology S.r.l. | |
| DB Elettronica Telecomunicazioni S.p.A. | Padua |
| DBridge | Milan |
| DCLabs | |
| De Vision Communication | |
| De' Sign S.C. | Venice |
| DEA Security S.r.l. | La Spezia |
| Dea System S.r.l. | Vicenza |
| Dealflower S.r.l. | |
| Debba.it | Genoa |
| Deca S.r.l. | Turin |
| Decodo | Bergamo |
| Deda Group | Trento |
| Dedalo AI S.r.l. | |
| Dedalus Global S.p.A. | |
| Deep Oean Capital SGR S.p.A. | |
| DeepTrace Technologies S.r.l. | |
| Deeva | |
| Deicon S.r.l. | Milan |
| Delcaldo | Pisa |
| Deliverart S.r.l. | |
| Delos S.r.l. | |
| Delphinet | Rome |
| Delta i S.r.l. | Massa-Carrara |
| Delta Ohm S.r.l. | Padua |
| Delta System S.p.A. | Treviso |
| Delta x Multimedia | Barletta-Andria-Trani |
| Deltatre | |
| DEMA S.p.A. | |
| Demal Elettronica S.r.l. | Forlì-Cesena |
| Demetrio Polimeno | Bologna |
| DemiSolutions | Rimini |
| DensityDesign | |
| Deply | |
| Derga Consulting S.r.l. | South Tyrol |
| Design.it | Milan |
| Designpro | Rome |
| DesoTech | Bari |
| Dev House | |
| devACADEMY | Turin |