| Saxon Computing | East Riding of Yorkshire |
| Saxon Digital Services | |
| Saxon Internet Solutions | Kent |
| Saxonica | Berkshire |
| Saxton IT Services | Warwickshire |
| Say Web Design Ltd | |
| SB Computers Superstore | Derbyshire |
| SB Designs UK | Staffordshire |
| SB Drug Discovery | Glasgow |
| SB Software | |
| SBC Solutions Ltd | Hampshire |
| SBC Systems (UK) Ltd | Greater London |
| SBK Computers Ltd | Derbyshire |
| SBN | |
| SC Media UK | Greater London |
| SC Systems Ltd | Hertfordshire |
| Scaffold Digital Ltd | Lisburn and Castlereagh |
| Scalable Software Ltd | Greater London |
| Scalar Enterprises | Hampshire |
| SCALER Software Solutions Ltd | |
| ScaleUp Institute | Kent |
| ScaleXP | |
| Scan.com | |
| Scancell | |
| Scancom Distribution Ltd | Leicestershire |
| Scanning & Data Solutions Ltd | Bedfordshire |
| ScanToPDF | Bristol |
| Scapa Technologies | East Lothian |
| Scaramanga Agency Ltd | |
| Scarfe Creative | Norfolk |
| Scarlet Design | Devon |
| Scarlet Therapeutics Ltd | |
| Scarycaravan Studios Ltd | |
| Scede | |
| Sceenic | |
| Scend Studio | Somerset |
| Scendea Ltd | |
| Scene Double Ltd | Hertfordshire |
| Scheme Trader Insurance Software | Merseyside |
| SchemeServe | |
| Schestowitz | Greater Manchester |
| Schnell Solutions Ltd | Greater London |
| Scholarcy Ltd | |
| School Cloud Systems | Glasgow |
| School Creations | Dorset |
| School of Advanced Study | Greater London |
| School of Code | |
| School of Code | |
| School of Mathematics Research | |
| School Software Company | Cambridgeshire |