| Skillus OÜ | |
| Skriining AS | Harju |
| SkyFMS OÜ | |
| Smart AD | Harju |
| Smart Soft Team | |
| SmartCap AS | Harju |
| SmartSender.io | |
| Snabb OÜ | |
| Snacka | |
| SnoopGame OÜ | |
| Soft8Soft OÜ | |
| Softreck | |
| Softronic Baltic AS | Harju |
| Solis BioDyne OÜ | |
| Solus Agency | |
| Solve.Care | |
| Sommelier | |
| Sona Systems Ltd | Harju |
| Soshace OÜ | |
| Spaceit | Tartu |
| Speak Languages OÜ | |
| Specialist VC | Harju |
| Spectro Finance OÜ | |
| Sportlyzer, LLC | Harju |
| Sports Gene OÜ | |
| ST Software | Harju |
| Star Cloud, LLC | |
| Startup Estonia | Harju |
| Startup Wise Guys | Harju |
| Stebby | |
| Stirling Ventures | Harju |
| Stockpoint OÜ | |
| Storadera | |
| Strateegiaturundus | Harju |
| Striga Technology OÜ | |
| STV AS | Harju |
| Sunly | |
| Superangel.io | Harju |
| Superangel.io | |
| Supervisely OÜ | |
| SupplierPlus Group OÜ | |
| Swapin | |
| Swaply Int OÜ | |
| Swedbank AS | |
| Swipelux OÜ | |
| Talkini OÜ | Harju |
| Tallinn University of Technology | |
| Tallinna Arvutikool OÜ | Harju |
| Tallinna Majanduskool | |
| Tallinna Tehnikakõrgkool | |