| Start With Data | |
| Startadesign Ltd | Hertfordshire |
| Starthawk | |
| StarTraq Ltd | Oxfordshire |
| Startup Coalition | |
| Startup Direct | Tyne and Wear |
| Startup Events List | |
| Startup Giants plc | |
| Startup Hosting | |
| Startup Leadership UK | |
| Startup Manufactory Ltd | Greater London |
| Startup Rise EU | |
| Startup Venture Builder | Greater London |
| Startupbootcamp | Greater London |
| Startups | |
| Startups Magazine | |
| Startups of London | |
| Startups Without Borders | |
| Stasis | |
| STAT7 | Greater London |
| State of European Tech | |
| Static Systems Group Ltd | |
| Station Cars Network | |
| Station Software | |
| StationX | Shropshire |
| Stats Perform | |
| Statuo Ltd | |
| StatusCake | |
| Staunton Rook Marketing Agency | |
| Staveley Communications | Greater Manchester |
| StaySafe Apps Ltd | |
| Staze Ltd | |
| Steadlands | Cardiff |
| SteadyGo Ltd | West Yorkshire |
| SteadyPay Ltd | |
| Stealth Electronics Ltd | Suffolk |
| Steama Company Ltd | |
| SteamJet Space Systems | |
| Steatite Ltd | Worcestershire |
| Steel City IT | |
| Steel River Consultants Ltd | |
| Steel Studios | |
| Steelcalc | Warwickshire |
| Steele Media Ltd | Norfolk |
| SteelEye Ltd | |
| Steff Potter | |
| Stellar Omada Ltd | |
| Stellar Search Marketing | Greater London |
| Stellastra Ltd | |
| STEM Learning Ltd | |