| Social Freaks | Plovdiv |
| SoCyber | |
| Sofia Angels Ventures | Sofia |
| Sofia Business School | Sofia |
| Sofia Computers | Sofia |
| Sofia Connect | Sofia |
| Sofia Development Association | Sofia |
| Sofia Investment Agency | Sofia |
| Sofia Tech Park | Sofia |
| Sofia University "St. Kliment Ohridski" - Faculty of Mathematics and Informatics | Sofia |
| Sofia Web Works | Sofia |
| Soft-I | Sofia |
| Soft2Run | Sofia |
| SoftART Ltd | Plovdiv |
| SoftART.bg | Plovdiv |
| Softaware Ltd | Sofia |
| SoftConsultGroup | Sofia |
| SoftGroup | Sofia |
| Softkey Bulgaria | Sofia |
| SoftShop | Sofia |
| SoftVisia | Sofia |
| Software Company Ltd | Sofia |
| Software Group | Sofia |
| Software Product Group | |
| Software Supreme | |
| Software University | Sofia |
| SoftwareONE Bulgaria EOOD | Sofia |
| Sorcible | Sofia |
| South Gate Tech | Sofia |
| Speedflow Bulgaria | |
| SSARM | Sofia |
| SSI.bg | Varna |
| ST6 | |
| Staking | |
| Standpoint | Sofia |
| Stanga1 | |
| Start It Smart | Sofia |
| Start.bg | Sofia |
| Startup BG | Sofia |
| StartUp Navigator | Sofia |
| Static.bg | |
| Stemo Ltd | Sofia |
| Stenisoft | Sofia |
| Stens Ltd | Sofia |
| Step-Soft | Sofia |
| StikCredit | Sofia |
| StivaSoft | Sofia |
| StorPool | Sofia |
| Stsoft | Dobrich |
| Studio X Digital | Sofia |