| qbk | Intuit QuickTax 2009 Backup |
| qbl | Intuit QuickBooks License File |
| qbmb | QuickBooks Backup |
| qbo | Intuit QuickBooks Online Bank Statement |
| qbp | Intuit QuickBooks Print File |
| qbquery | MySQL Query Browser Saved SQL Query |
| qbs | Navicat for MySQL Query Builder Tables Data |
| qbt | Intuit QuickBooks Temporary File |
| qbt | Qubicle Binary Tree Data |
| qbz | Quick Trial Balance Data File |
| qcc | QC-Calc Data Collection |
| qch | QT Compressed Help |
| qch | Intuit Quicken for DOS Data File |
| qci | Cliq Accessories Phonebook Index |
| qck | Jigsaw 2 Quickcharts Data |
| qcl | Quark Color Library |
| qcm | 3164 Emulator Quick Command |
| qcn | QPST Content |
| qct | Quick Chart Data |
| qd | Sharp MZ-series Emulator Quick Disk Data |
| qd0 | Omnis Quartz Segment 10 Data |
| qd3 | Omnis Quartz Segment 3 Data |
| qd4 | Omnis Quartz Segment 4 Data |
| qd8 | Omnis Quartz Segment 8 Data |
| qda | KaleidaGraph Data |
| qdat | QuickTime Install Cache |
| qdb | Quicken Data Backup |
| qdc | Quick Devis Database |
| qdd | Snapform Designer Binary Data |
| qdd | Rimage QuickDisk Job Data |
| qdes | DatabaseSpy Design Data |
| qdf | Quicken Data |
| qdf-backup | Intuit Quicken Data Backup |
| qdfm | Intuit Quicken for Mac Data File |
| qdfx | Intuit Quicken Financial Exchange File |