| SimplyCast | Nova Scotia |
| SimplyCité | Quebec |
| SimplyHelp.ca | |
| SimplyPHP | |
| Simport Scientific, Inc. | |
| Simpson Home Computer Support | Manitoba |
| Simpson Telecom Group | Ontario |
| Simtech CNC Consultants, Inc. | Quebec |
| Simulab3D | |
| SimWave Consulting, Inc. | Ontario |
| SimWell Consulting & Technologies, Inc. | |
| Simzer Design | Ontario |
| Sincerus Capital Ltd | |
| Sinclair Technologies | Ontario |
| Sing Digital, Inc. | Alberta |
| Single Entry Point | Ontario |
| Single Quantum Systems, Inc. | |
| SingleKey | |
| Singsquid | Quebec |
| Singular Media | Ontario |
| Singular Systems | Alberta |
| Sintalica Bioscience Corporation | |
| Sion Software | British Columbia |
| Sippy Software, Inc. | |
| SIR Solutions | Quebec |
| SIRE Brands, Inc. | Ontario |
| Sirf IT Solution | |
| Sirius Conseils | Quebec |
| Sirius microSystems | Ontario |
| Sirius Technologies | Manitoba |
| SIRKit | Alberta |
| Siron Technologies Group, Inc. | Ontario |
| Sirona Biochem Corporation | |
| SIS Consulting | Ontario |
| Sisarich Group | |
| Siscom Group | Ontario |
| Sisnarine Technologies, Inc. | |
| Sistema Logistics | Quebec |
| Site 20/20 | |
| Site Safety Solutions, Inc. | |
| Site-Secure Software | Ontario |
| Site2Site | |
| SiteAlive, Inc. | Ontario |
| SiteCloud | New Brunswick |
| SiteExact | |
| SiteFB.com | Ontario |
| Sitek Systems | British Columbia |
| Sitely Pro | |
| SiteMax Systems, Inc. | |
| SiteProNews | Manitoba |