| SOMOS.plus | Málaga |
| Sonicat Systems | Barcelona |
| Sortes Ingeniería Informática, S.L.U. | Madrid |
| SOS Informática Soluciones TIC Salamanca | Salamanca |
| SOS mipc | Madrid |
| Sosmatic | Barcelona |
| Sothis | Valencia |
| South Summit | |
| Soy.es | Alicante |
| Sozpic | Murcia |
| Spacecreator | Barcelona |
| Spacer Web Hosting | Cádiz |
| Spain Business School | |
| Spanish Proptech | Madrid |
| Spanish Startups | Madrid |
| Spanto Soft | Girona |
| SPC | Álava |
| Spin Media, S.L. | Madrid |
| SPIN, S.A. | Barcelona |
| SpiraleBackup | Zaragoza |
| SpliceBio, S.L. | Barcelona |
| Spotahome | |
| SpotLab | Madrid |
| Spring I/O | Barcelona |
| Spuch | A Coruña |
| SQUAADS | |
| Squizzo | Barcelona |
| SR Tecnologías Aplicadas | Madrid |
| SRI TEIN, S.L. | Las Palmas |
| ST Visual | Madrid |
| STAb Therapeutics | |
| StageInHome | Barcelona |
| Stampery | Madrid |
| Stand Up Negocios Online | |
| Star2Billing, S.L. | Barcelona |
| Stark Future | Madrid |
| Starlab Barcelona, S.L. | |
| Starshot Solutions, S.L. | Lleida |
| Start Up | Asturias |
| Startidea Málaga, S.L. | Málaga |
| Startify | Madrid |
| Startup Europe Week | Madrid |
| Startup Grind Barcelona | Barcelona |
| Startup Hub Catalonia | Barcelona |
| StartUp Labs Spain | Sevilla |
| Startup Radar Madri+d | Madrid |
| Startup Valencia | |
| Startups Real | |
| Startups' Oasis | Madrid |
| Statkraft | |