| stm | Nanoeducator File |
| stm | SmartWare Appointment Data |
| stm | STELLA Model |
| stmb | Synclavier Timbre Data |
| stmi | Adobe PageMill Data |
| stmod | solidThinking Inspire Model |
| stmx | STELLA Model Data |
| stoc | UMDES FSM Stochastic Data |
| storyisttheme | Storyist Theme Data |
| stot | Mac OS X Help Index |
| stp | MotionTracking Statistic Filters and Masking Parameters Data |
| stp | Tekla STEP Data |
| stp | WSxM SPM Processed Data |
| stpg | STP Gate Phonebook Data |
| stppk | SDL Trados Synergy Project Package |
| stpx | SchemaType Compiled Schema |
| str | Altair FEKO Solution Vector Data |
| str | DataPerfect Structural Information Data |
| str | dBASE Structure Object |
| str | STATISTICA Report File |
| str | STELLA Runtime |
| string | UltraEdit String Data |
| string | Zoom Player General Text Data |
| strn | HyperCard Stack Converter Data |
| sts | AdriPSX Save State |
| sts | MemMaker Status Information File |
| sts | Nimbus 7 SAMS Status Data |
| stt | Streets & Trips Map Template |
| stv | SofTV Author File |
| stx | SAS XPORT Transport File |
| sty | Tecplot 360 Style Data |
| styk | Stykz Stick Figure |
| stykz | Stykz Animation File |
| styles | Steam Client GUI Resources Data |
| styx | ChordWizard Songtrix Style Data |