| AppointMentor | |
| Appoly | Warwickshire |
| Apposite Capital, LLP | |
| Approach Direct Marketing | |
| Appropriate Solutions | Cumbria |
| ApprovalMax | |
| Approved Index | |
| Apps in My Pocket | |
| Apps IT Ltd | |
| Apps On The Move Ltd | |
| Apps Plus | West Midlands |
| Appsecco | |
| AppShed Ltd | |
| Appsmakerstore | |
| AppsPlus | |
| Appsumer | |
| AppSynergies | |
| Apptaura | |
| Apptituda | |
| Apptivation Mobile Ltd | |
| Appuals | Dorset |
| Appurity | |
| AppWeb | |
| Appy Monkey | |
| Appy Ventures Productions Ltd | |
| AppyParking | |
| AppyWay | |
| Apricot | Gloucestershire |
| Apritel Communication Services | Hampshire |
| Aprompt | Wiltshire |
| Apron Payments Ltd | |
| APT Ltd | Greater London |
| APT Solutions Ltd | Shropshire |
| Apteco Ltd | Warwickshire |
| Aptem Ltd | |
| Apterna Ltd | |
| Aptitude Agency Ltd | |
| Aptitude Software Ltd | |
| Aptive Consulting Ltd | Surrey |
| Apto Solutions | Bristol |
| Apto-Gen Ltd | |
| APVentures | |
| Aqdot Ltd | |
| Aqilla | |
| aql | West Yorkshire |
| AQUA Social | |
| Aquaforest | Buckinghamshire |
| Aquaman Design | |
| Aquamarine Media | |
| Aquamatix Ltd | |