| Diagrams.net | |
| Dialog Semiconductor (UK) Ltd | Berkshire |
| Diamond Computers | East Sussex |
| Diamond Discovery Software Ltd | Bridgend |
| Diamond Electronics Ltd | Cheshire |
| Diamond Light Source Ltd | |
| Dicey Tech | |
| Dicontas Ltd | South Lanarkshire |
| Dictating Solutions | Greater Manchester |
| Didomi | Greater London |
| Diffblue Ltd | |
| Different Gravy Digital | |
| Different Projects | |
| Diffusion Digital | Greater London |
| DiffusionData | |
| DigbyEdwards | |
| Digi Gbox Ltd | |
| Digi Rush Solutions | |
| Digi.me | |
| Digichamp Ltd | |
| DigiCreDis | |
| Digidom Studios Ltd | |
| Digimap Ltd | Channel Islands |
| DigiMarCon UK | |
| Digiryte Ltd | |
| DigiScript | |
| DIGISEQ | |
| Digismarties Ltd | |
| DIGIT | Edinburgh |
| Digital Aesthetics | |
| Digital Applications International Ltd | Aberdeenshire |
| Digital Approach | |
| Digital Arts Creative | Staffordshire |
| Digital Automation | |
| Digital Autopsy UK | |
| Digital Barriers | |
| Digital Beans | Kent |
| Digital Birmingham | West Midlands |
| Digital Bricks | |
| Digital Britain Forum | |
| Digital Catapult | |
| Digital Clarity | Surrey |
| Digital Consortium Ltd | |
| Digital Converters | |
| Digital Creative PRO | |
| Digital Daffodil Ltd | Hertfordshire |
| Digital Data Ltd | |
| Digital Design Online | |
| Digital Detective Group Ltd | Kent |
| Digital Dexterity Ltd | Glasgow |