| JCP Consulting Ltd | |
| JCR Systems Ltd | |
| JCS Computerent | Northamptonshire |
| JCT Consultancy Ltd | |
| JCT Designs | Carmarthenshire |
| JCWORKS Ltd | |
| JD Commerce Ltd | |
| JD Compucare | |
| JD Design | Staffordshire |
| JDC Digital Ltd | |
| JDD Agency | |
| JDR Cable Systems Ltd | Edinburgh |
| Jeff Logan | Wiltshire |
| Jellagen | |
| Jellyfish Digital Group Ltd | |
| Jellyfish Digital Group Ltd | |
| Jellyfish Group | Greater London |
| Jellymedia Ltd | |
| Jellypie Ltd | Hertfordshire |
| Jemco Associates | Glasgow |
| Jemford | West Midlands |
| Jendev | |
| Jenesys | |
| Jenkin Hill Internet | Cumbria |
| Jenner Institute | |
| Jennings Computer Engineering Ltd | |
| Jennings Computer Services Ltd | North Yorkshire |
| Jensen & Jensen Ltd | |
| Jenson Ventures | |
| JeraSoft | Greater London |
| Jerboa | Monmouthshire |
| Jerry Lampson | South Yorkshire |
| Jersey Finance Ltd | |
| Jester Interactive Publishing Ltd | Denbighshire |
| Jet Design and Marketing | |
| Jet Engineering | |
| Jet Tec | Lincolnshire |
| Jet Web Design | Bristol |
| Jewelion Web Design | Shropshire |
| Jezebel Design | West Yorkshire |
| JezUK | West Midlands |
| JG Digital Web Design & Development | |
| JG Technologies Ltd | |
| JGBM Ltd | Devon |
| JGM Consulting | |
| JGS Web Design | West Yorkshire |
| JGTHMS Ltd | |
| JH Signage | |
| jhTuppeny Consulting Ltd | Surrey |
| Jianway Ltd | Hertfordshire |