| loop | Apple Soundtrack Pro Loop Data |
| loov | SmadAV Virus Definitions |
| lop | MasterCook Layout Data |
| lov | SAP Business Objects LOV File |
| loxplan | Loxone Miniserver Program |
| lp | Lightscape Preparation File |
| lp7 | LP7 Digitally Signed Data |
| lpa | LPA View Data |
| lpd | Helix Nuts and Bolts File |
| lpdb | Librarian Pro Database |
| lpl | LPL Model |
| lpm | WonderBit Life Photo Maker Data |
| lpmd | LPMD Molecular Data |
| lpn | LVPLAN Data |
| lps | Bryce 7 Leaf Shape |
| lpsx | LARSA 4D Section Database |
| lpv | Lasergraph DSP Laser Show Preview Data |
| lpw | IRIS Laserforms Lforms Data |
| lpx | LaTeXPiX Script |
| lqa | LabQuest 2 Automatic Update |
| lqf | LeechFTP Saved Queue |
| lqm | Liquid Audio Master Data |
| lqn | CoWolf Layered Queuing Network Data |
| lqp | Liquid Audio Player Passport Data |
| lqs | Libvirt Qemu Saved Data |
| lqu | LeapFTP Queue Data |
| lra | HPE LoadRunner Analyzed Results |
| lrcat | Adobe Photoshop Lightroom Catalog |
| lrcx | KwMusic Data |
| lrdata | Adobe Photoshop Lightroom Data |
| lrdb | Adobe Photoshop Lightroom 1.0 Database |
| lrl | SmartWare Local Resource Library |
| lrm | Microsoft Encarta Class Server Learning Resource Module |
| lrpreview | Adobe Photoshop Lightroom Preview |
| lrq | GEAR License Request File |