| Extension | File Type | Files scanned | Contributor |
| Q | Callahans Crosstime Saloon video/animation | 2 | |
| Q | Legend Entertainment Q video/animation (generic) | 9 | |
| Q | Mission Critical video/animation | 37 | |
| Q/PAK | Quantum compressed archive | 15 | |
| Q | Shannara video/animation | 118 | |
| Q3C | Quick 3D Cover project | 4 | |
| Q3O | Quick3D Object | 44 | |
| Q3S | Quick3D Scene | 2 | |
| Q4 | XLD4 bitmap | 31 | |
| Q4D | XLD4 Graphic Data Document bitmap | 5 | |
| QAR | Quartus II Archive | 3 | |
| QAT | Office Quick Access Toolbar info | 5 | |
| QAT | TradeStation Quote window configuration | 8 | |
| QBB | Intuit QuickBooks Backup | 6 | |
| QBE | dBASE 5.0 Query | 4 | |
| QBE | dBASE IV Query | 3 | |
| QBO | dBASE compiled Query | 4 | |
| QBTHEME | qBittorrent Theme | 18 | |
| QBW | Intuit QuickBooks for Windows | 9 | |
| QCF | Q-emulator Configuration | 12 | |
| QCF | Quickbasic Coordinates File | 2 | |
| QCL | QuarkXPress Color Library | 12 | |
| QCMP | QuickCompression compressed data (BE) | 2 | |
| QCOW/IMG | QCOW disk image (gen) | 5 | |
| QCOW/IMG | QCOW1 disk image | 4 | |
| QCOW2/IMG | QCOW2 disk image | 7 | |
| QCOW3/IMG | QCOW3 disk image | 2 | |
| QCP | QualComm PureVoice | 20 | |
| QD | FlashFloppy Quick Disk image | 2 | |
| QD | HxC Floppy Emulator QuickDisk image | 4 | |
| QDA | Akuji the Demon game data archive | 4 | |
| QDA | Pendulumania game data | 4 | |
| QDA | Quadruple D Archiver compressed archive | 4 | |
| QDAT | QuickTime installer cache | 4 | |
| QDB | Quartus Database File | 133 | Huy Nguyen |
| QDB | Quick Database | 5 | |
| QDC | Garmin Quickdraw Contours data | 3 | |
| QDF | Quicken data | 3 | |
| QDIM | PointCab QDIM elevation map | 30 | |
| QDS | Genstat QTL Data Space | 4 | |
| QDTP | Tourenplaner data | 10 | |
| QE | QuickEntry form (v1.1) | 3 | |
| QED | QEMU Enhanced Disk Image | 2 | |
| QEF | Qubicle Exchange Format | 2 | |
| QF | Ovi Maps info | 9 | |
| QFC | QuickFileCollection archive | 6 | |
| QFC | QuickFileCollection archive (v3) | 7 | |
| QFILTER | Apple Quartz Filter | 6 | |
| QFX | QuickLink II Fax bitmap (new) | 3 | |
| QFX | QuickLink II Fax bitmap (old) | 6 | |
| QFX | Quicken Transfer file | 7 | |
| QGS | QGIS project | 124 | |
| QGZ | QGIS Zipped project | 6 | |
| QHCP | Qt Help Collection Project | 10 | |
| QHP | Qt Help Project | 9 | |
| QIC | Windows 98 MSBackup backup set | 5 | |
| QIF | Quality Information Framework document | 66 | |
| QIF | Quicken Interchange Format | 9 | |
| QIP | Altera Quartus IP | 12 | |
| QIP | Quarterdeck Installation Package (v1) | 2 | |
| QIP | Quarterdeck Installation Package (v2) | 17 | |
| QIX | GeoTools shapefile spatial index | 4 | |
| QLB | Microsoft Basic Quick library | 86 | |
| QLB | Microsoft VBDOS Quick library | 11 | |
| QLI | Statler Stitcher | 6 | |
| QLL | Quattro Pro add-in functions library | 2 | |
| QLPAK | Q-emuLator Package | 9 | |
| QLR | QGIS Layer | 10 | |
| QM | Qt Message | 55 | |
| QMBL | LabQuest results | 21 | |
| QMC | MST Quintus Macro | 2 | |
| QMD | QGIS MetaData | 13 | |
| QMG | Qmage encoded data | 7 | |
| QML | QGIS style | 66 | |
| QMLC | QML Cached document | 1150 | |
| QMV | QMovie Video | 3 | |
| QOA | Quite OK Audio | 3 | |
| QOI | Quite OK Image Format bitmap | 7 | |
| QOIR | QOIR bitmap | 13 | |
| QOP | 3ds Quad colors | 18 | |
| QP03 | qpress compressed archive | 18 | Label |
| QPE | Qualitas Program Information | 2 | |
| QPF | Quartus Prime Project File | 80 | Huy Nguyen |
| QPL | Quoter Plan project | 6 | |
| QPM | QNX Package Manifest | 206 | |
| QPT | QGIS Composer Template | 26 | |
| QPU | Microsoft QuickPascal Unit | 7 | |
| QPW | Quattro Pro for Windows spreadsheet | 21 | |
| QPX | QVox external plugins configuration | 6 | |
| QR2 | Delphi QuickReport | 20 | |
| QRC | Qt Resource Collection | 24 | |
| QRM | Allen Communications Quest Released Module (v5) | 15 | Kieran O'Donnell |
| QRM | QNX Repository Manifest | 6 | |
| QRM | RM/Quest module | 60 | |
| QRP | Gupta ReportWindows Report | 9 | |
| QRP | QuickReport Report | 8 | |
| QRS | SlickRun MagicWord Pack | 6 | |
| QRT | QR-Tekst document (DOS, 5.x) | 4 | |
| QRT | QR-Tekst document (Win, 1.x) | 6 | |
| QRT | QR-Tekst document (Win, 2.x) | 8 | |
| QRT | QR-Tekst document (generic) | 17 | |
| QRT | QRT Ray Tracer scene description (with rem) | 12 | |
| QRY | ACT! Win Query | 7 | |
| QSD | Quicken Win Data | 14 | |
| QSF | Micrografx QuickSilver graphic plugin | 3 | |
| QSF | Quartus Prime Settings File | 71 | Huy Nguyen |
| QSF | Quartus Setting File (by Terasic System Builder) | 6 | |
| QSF | Quartus Setting File (generic, with rem) | 19 | |
| QSF | Quintessential Player Family Skin | 16 | |
| QSFLIB | QSF Capcom QSound Format rip | 8 | |
| QSK | Quintessential Player Kid Skin | 10 | |
| QSQ | QSEQ project | 4 | |
| QSS | File Express Quick Scan | 4 | |
| QST | HeroQuest Quest | 18 | Kristopher Neidecker |
| QST | Zelda Classic Quest | 2 | |
| QSU | Zelda Classic Quest (Unencoded) | 2 | |
| QSYS | Altera Qsys System | 20 | |
| QTCH | Quicktime Cached data | 4 | |
| QTIF/QIF | QuickTime Image Format bitmap | 6 | |
| QTIF/QIF | QuickTime Image Format bitmap (alternate) | 3 | |
| QTK | Apple QuickTake 100 photo | 2 | |
| QTK | Apple QuickTake 150 photo | 23 | |
| QTL | QuickTime Media Link | 7 | |
| QTP | QuickTime Preferences | 7 | |
| QTR | Qtractor session | 6 | |
| QTT | Qtracker Theme | 6 | |
| QTX | Datacolor QTX format (batch) | 14 | |
| QTX | Datacolor QTX format (standard) | 25 | |
| QTZ | Quartz Composer data | 31 | |
| QUA | Avira AntiVir Quarantined | 3 | |
| QUA | Avira AntiVir Quarantined (var.) | 27 | Joerg Jenderek |
| QUA | FileMedic Antivirus Quarantined | 5 | |
| QUAKEML | QuakeML seismological data | 8 | |
| QUANTIZED | BASIC8 Quantized image | 5 | |
| QUERY | Microsoft PCHealth query | 6 | |
| QUEST | Quest adventure (v5) | 57 | |
| QUEST-SAVE | Quest 5 game Save | 25 | Meus Artis |
| QUOX/QUIZ | Question Object File Format | 8 | |
| QVM | Project IGI: I'm Going In save game | 4 | |
| QVW | QlikView document | 57 | roentgen |
| QW | QandA Write for Windows document (v3.0) | 16 | |
| QWC | QuickBooks Web Connector configuration | 8 | |
| QWK | QWK offline mail packet (ZIP compressed) | 17 | |
| QWS | Quartus Workspace | 12 | |
| QX | Quexal sourcecode | 9 | |
| QXCF | Q Light Controller+ Color Filters | 4 | |
| QXD/QXP | QuarkXPress Document/Project (generic) | 12 | |
| QXF | Q Light Controller+ Fixture definition | 937 | |
| QXI | Q Light Controller+ Input profile | 25 | |
| QXM | Q Light Controller+ Midi template | 8 | |
| QXM | Quexal macro | 12 | |
| QXMT | Q Light Controller+ Modifier Template | 14 | |
| QXW | Q Light Controller+ Workspace | 10 | |
| QZ | Create A Quiz file | 2 | |
| QZD/QZE/QZS | QuizPro quiz data | 9 | |
