| Codetank | |
| Codethink Ltd | Greater Manchester |
| Codevate Ltd | |
| Codeworks | |
| Codex Media | |
| CodeYourFuture | |
| Codify Ltd | Aberdeen |
| Coding.bio | |
| Codora | |
| Coeus Software Ltd | |
| Coffee Black | West Midlands |
| Cogapp | |
| CogBooks Ltd | |
| Cogent Focus | Perth and Kinross |
| Cognetivity Neurosciences Ltd | |
| Cognica | Wiltshire |
| Cognidox Ltd | Cambridgeshire |
| Cognino.ai | |
| Cognism Ltd | |
| CogniSoft Ltd | Greater Manchester |
| Cognitive.Business Ltd | |
| Cognito iQ | Berkshire |
| Cognito Learning | |
| Cognitronics Ltd | Nottinghamshire |
| Cogsy | |
| Coherent | |
| Cohort Computers Ltd | Dorset |
| Cohort Studios Ltd | |
| Coin Market Manager | |
| Coincover | |
| CoinCover | |
| Coincrete | |
| CoinMode | |
| CoinShares | |
| Coinsilium (Gibraltar) Ltd | |
| Colbek Systems Ltd | Warwickshire |
| Colchester Web Design | Essex |
| Colcom Ltd | |
| Coleg Sir Gâr | |
| Coleg y Cymoedd | |
| Coleswood Media | |
| Colewood Internet Ltd | County Durham |
| Colinton Website Design | Edinburgh |
| Coljam Consultants Ltd | Perth and Kinross |
| Collabco Ltd | |
| Collabit Software Ltd | |
| Collabor8online | |
| Collabora Ltd | Cambridgeshire |
| Collabora Ltd | |
| Collaborative Computational Project No. 4 | Oxfordshire |