| .VPB | Unknown Developer | File con immagini raster | Quantel VPB Image Format | Unknown Software | Unknown Developer |
| .VQE | Yamaha Corporation | File audio | Yamaha Sound-VQ Locator File | Unknown Software | Unknown Developer |
| .VQL | Yamaha Corporation | File audio | Yamaha Sound-VQ Locator File | Unknown Software | Unknown Developer |
| .VRA | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .VSR | Microsoft Corporation | File di database | Microsoft Access Report | Unknown Software | Unknown Developer |
| .VT | Unknown Developer | File di dati | VT100 Terminal Data File | Unknown Software | Unknown Developer |
| .VUX | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .VXX | Unknown Developer | File di sistema | IOsubsys | Unknown Software | Unknown Developer |
| .VYB | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .W2F | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .W73 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .WC4 | Unknown Developer | File vari | WinCheckIt4 Settings File | Unknown Software | Unknown Developer |
| .WEBARCHIV | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .WEI | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WF2 | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WINDOWSLIV | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WINDOWSMED | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .WLF | Microsoft Corporation | File di dati | Microsoft Windows 98/Me Dr. Watson Log | Unknown Software | Unknown Developer |
| .WLO | JinKe Electronic Company | File eBook | WOLF eBook | Unknown Software | Unknown Developer |
| .WLT | Unknown Developer | File grafici | WaveL Wavelet Compressed Graphic | Unknown Software | Unknown Developer |
| .WMH | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .WMO | World Meteorological Organization | File di dati | WMO Binary Format File | Unknown Software | Unknown Developer |
| .WSQ | UTAU Team | File audio | UTAU File | Unknown Software | Unknown Developer |
| .WS_ | Unknown Developer | File di settaggi | Visc15 Adressen Setup File | Unknown Software | Unknown Developer |
| .WVT | Unknown Developer | File di dati | Compuwx Export Data | Unknown Software | Unknown Developer |
| .WWZ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .WXW | WiNRADiO | File vari | WiNRADiO Extended Wave File | Unknown Software | Unknown Developer |
| .X23 | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .X2M | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .X33 | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .X3M | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .XACT | XactSystems | File vari | XactScript File | Unknown Software | Unknown Developer |
| .XAD | Riven the Mage | File audio | eXotic ADlib Sound Format File | Unknown Software | Unknown Developer |
| .XAK | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .XB~ | Unknown Developer | File vari | IC File | Unknown Software | Unknown Developer |
| .XCK | Unknown Developer | File di dati | Extended Crack File | Unknown Software | Unknown Developer |
| .XD | Unknown Developer | File di dati | CCS-lib.2 Examples Motif-CC File | Unknown Software | Unknown Developer |
| .XDE | Unknown Developer | File 3D | Tgif-3.0 File | Unknown Software | Unknown Developer |
| .XDSL | D-Link Corporation | File di sistema | D-link Router UK Firmware Update File | Unknown Software | Unknown Developer |
| .XED | Unknown Developer | File di dati | XED Chemical Modeler Input/Output Data | Unknown Software | Unknown Developer |
| .XI1 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .XLTD | Unknown Developer | File vari | Thunder Temporary Data File | Unknown Software | Unknown Developer |
| .XMAS | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .XMIT | IBM | File di dati | IBM XMIT Data | Unknown Software | Unknown Developer |
| .XNX | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .XOS | Xaos Tools | File con immagini raster | Xaos Tools Bitmap Image | Unknown Software | Unknown Developer |
| .XPE | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .XPN | Quest Software | File vari | Quest Saved Explain Plan | Unknown Software | Unknown Developer |
| .XSEND | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .XT* | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .XTE | PerkinElmer | File di dati | LabChip XTe Data | Unknown Software | Unknown Developer |
| .XUP | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .XVID-TRL | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .XWF | Nuance | File vari | OmniPage Workflow File | Unknown Software | Unknown Developer |
| .XWT | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .XXC | CentraLine | File di dati | Centraline COACH Controller Firmware | Unknown Software | Unknown Developer |
| .XXX | BloodDolly | File criptati | TeslaCrypt 3.0 Ransomware Encrypted File | Unknown Software | Unknown Developer |
| .XXXX | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .XXZ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .XZP | Unknown Developer | File di dati | XZP Container Format | Unknown Software | Unknown Developer |
| .YAD | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YAR | Unknown Developer | File compressi | YAK Compressed Archive | Unknown Software | Unknown Developer |
| .YC | Unknown Developer | File compressi | YAC Compressed Archive | Unknown Software | Unknown Developer |
| .YIN | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YJF | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .YKI | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .YLM | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YN | Unknown Developer | File compressi | Audio Utility Tuningwrench Compressed File | Unknown Software | Unknown Developer |
| .YNM | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YNX | Unknown Developer | File audio | Segmax Seqprest Compressed File | Unknown Software | Unknown Developer |
| .YRA | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .YTS | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YUF | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .YYC | Unknown Developer | File di dati | Wave Sapphire Distribution File | Unknown Software | Unknown Developer |
| .YZF | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZAE | Unknown Developer | File di dati | ZAwinEHE Project | Unknown Software | Unknown Developer |
| .ZAL | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZAX | Zaxcom | File audio | Zaxcom Audio Data | Unknown Software | Unknown Developer |
| .ZBJ | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZBX | Unknown Developer | File vari | Disk Volume Identification | Unknown Software | Unknown Developer |
| .ZCH | Unknown Developer | File vari | ZIG Game Construction Kit Data | Unknown Software | Unknown Developer |
| .ZDB | Synacor Inc. | File di dati | Zimbra Database File | Unknown Software | Unknown Developer |
| .ZDE | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZDF | Unknown Developer | File di dati | Zone Definition File | Unknown Software | Unknown Developer |
| .ZDI | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZEB | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZET | Unknown Developer | File compressi | ZET Compressed Archive | Unknown Software | Unknown Developer |
| .ZFSENDTOTA | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZGZ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZH3 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZIQ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZONE | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .ZPAR | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZPKG | Zyxel Communications | File eseguibili | Zyxel NSA-32x Application Package | Unknown Software | Unknown Developer |
| .ZR4 | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZUC | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .ZUN | Unknown Developer | File vari | Recogsp File | Unknown Software | Unknown Developer |
| .ZVQ | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ZXF | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .Z•À_•À_P | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
di 13 
