| stak | HyperCard Stack Data |
| stam | STAToolkit Metadata |
| stan | Stan Model File |
| stap | STAToolkit STAP Data |
| startupinfo | E-Prime StartupInfo File |
| stat | EnergyPlus Weather Data Summary Report |
| stat | SAM Training Statistics Data |
| state | Uplay State Data |
| state | Windows Photo Gallery State File |
| states | IconX Preset Data |
| stats | FreeSurfer Statistics File |
| status | uDraw Graph Status Data |
| stb | Autodesk AutoCAD Plot Style Table Data |
| stbom | Catia SmartBOM Data |
| stc | BrainVoyager QX Slice Time Course Data |
| stc | eSignal Stretch Chart Data |
| std | Prosa State Transition Diagram Graphics 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 |
| stf | PhotoImpression Thumbnail Cache |
| stf | Spanish Whiz Data |
| stfx | SampleTank 2 Effects Settings |
| stg | Microsoft ActiveSync Mobile Device Backup |
| stg | RSView Machine Edition Status Data |
