| Swift Digital Solutions | Greater London |
| Swift Internet | |
| Swift IT | Buckinghamshire |
| Swift IT Computer Services | |
| SwiftTec | Somerset |
| Swiipr Technologies | |
| Swindon Design & Development Ltd | Wiltshire |
| Swipe & Tap | |
| Swipii | |
| Swirrl IT Ltd | Greater Manchester |
| Switch | |
| Switch Computer Support | Devon |
| Switch Creative Ltd | |
| Switch Energy & Telecoms | |
| Switchnet Systems Ltd | |
| Swof Media, LLP | |
| SWS Broadband | Shropshire |
| Swytch Mobile Ltd | |
| Sy Brand | |
| SY Electronics | Greater Manchester |
| Sybaris Ltd | |
| Sycos AES | Dorset |
| Sycous | West Yorkshire |
| Syedain & Co. | |
| Sygem Software | Berkshire |
| Sygnature Discovery Ltd | |
| Sylvera Ltd | |
| Symatrix Ltd | Greater Manchester |
| SymbaSync Ltd | |
| Symbiant | West Yorkshire |
| Symbios Group | Hampshire |
| Symbiosis | West Yorkshire |
| Symbiosis Pharmaceutical Services | Stirling |
| Symfonie Capital | Greater London |
| Symmetrical | |
| Symphony | South Yorkshire |
| Symphony Ltd | Wiltshire |
| Symstar IT | Greater London |
| SymTerra | |
| Syn-Star PC Store | Hampshire |
| Synairgen plc | |
| Synap Learning Ltd | West Yorkshire |
| Synapse Network | |
| Synaptec Ltd | Glasgow |
| Synaptiv, Inc. | |
| Synaptiv, Inc. | |
| Synaxis Data Services Ltd | Greater Manchester |
| Synbiosis | |
| Synchtank | |
| Syncline | Greater London |