| stam | STAToolkit Metadata |
| stan | Stan Model File |
| startupinfo | E-Prime StartupInfo File |
| stat | EnergyPlus Weather Data Summary Report |
| stat | SAM Training Statistics Data |
| state | Windows Photo Gallery State File |
| states | IconX Preset Data |
| stats | FreeSurfer Statistics File |
| status | uDraw Graph Status Data |
| stbom | Catia SmartBOM Data |
| stc | BrainVoyager QX Slice Time Course Data |
| stc | eSignal Stretch Chart Data |
| std | STAAD Model Data |
| stdf | SEDana Standard Test Data Format Data |
| stdid | RSA Soft Token Seed |
| stdl | Swift To-Do List Database |
| stdsrcmdl | Softimage Standard Source Model |
| steamstart | Valve Steam Start |
| stencyl | Stencyl Game Data |
| step | Tekla STEP Data |
| stfx | SampleTank 2 Effects Settings |
| stg | Microsoft ActiveSync Mobile Device Backup |
| stg | STATISTICA Graphics Data |
| sth | Lotus Domino Stash File |
| sti | STATISTICA In-place Database |
| stip | SampleTank 2 Instruments Preset |
| stk | Hyperstudio Stack Data |
| stk | Pivot Animator Stick Figure |
| stkx | Personal Stock Streamer Portfolio Data |
| stl | Macromedia Fireworks Style Library |
| stm | Microsoft Exchange Streaming Media File |
| stm | Nanoeducator File |
| stm | SmartWare Appointment Data |
| stm | STELLA Model |
| stma | eXtendable Wad Editor STMA Data |
