| WTS Technologies Ltd | |
| Wu Wo | Bristol |
| Wurkhouse | |
| WWS Webservices | Shropshire |
| Wx.company | |
| Wyatt International | West Midlands |
| Wychem | |
| Wye Valley Associates Ltd | Derbyshire |
| Wyenet Ltd | Herefordshire |
| Wyld Networks Ltd | Cambridgeshire |
| Wynne Digital | Greater London |
| WYSPR Ltd | |
| Wyvern Business Systems Ltd | Herefordshire |
| Wyze Ltd | Leicestershire |
| Wyzkey Ltd | |
| X-Europe | |
| X-Lab Ltd | West Yorkshire |
| X-on Cloud Communications | Suffolk |
| X-Press Digital Ltd | Derbyshire |
| X.act Systems Ltd | Derbyshire |
| x2cms Web Solutions | Glasgow |
| XA Digital Ltd | |
| Xact | |
| Xampla | |
| Xanadutec | |
| Xanalys | Greater Manchester |
| Xanda Ltd | Greater London |
| Xander Marketing Ltd | |
| Xapian | Hertfordshire |
| Xapien | |
| Xapo Bank | Gibraltar |
| Xapo Holdings Ltd | |
| Xara Xtreme | Hertfordshire |
| xAssets | Wiltshire |
| Xavier Analytics | |
| XBT Telephone Engineers | Devon |
| XC360 | Greater London |
| XCL Group Ltd | West Yorkshire |
| XCommNet Ltd | |
| XDelta | Bristol |
| xDox Ltd | Berkshire |
| Xebit Ltd | Worcestershire |
| XeBusiness | Greater Manchester |
| Xelix | |
| Xen Project | |
| Xen Solutions Ltd | Greater London |
| Xen-Tools.org | Cambridgeshire |
| Xencentric Hosting | Greater London |
| Xenogenix Ltd | |
| XEPOS | |