| .!UT | BitTorrent | Uncommon Files | uTorrent Incomplete Download | uTorrent | BitTorrent |
| .&&& | Safer Networking Ltd. | Uncommon Files | Temporary (Temp) File | FileAlyzer | Safer Networking Ltd. |
| .0.008 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.01 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.1 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.101 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.2 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.214 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0.264 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .00 | Toys for Bob | Uncommon Files | The Ur-Quan Masters Saved Game Slot 0 File | The Ur-Quan Masters | Toys for Bob |
| .000 | Microsoft Corporation | Uncommon Files | Indexing Service Data File | Microsoft Windows | Microsoft Corporation |
| .000D0-2016 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .01S | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .05B | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .07_T3 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .09S | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0A | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .0AR | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .0E | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .0GR | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .0HA | Unknown Developer | Uncommon Files | Maestro Mama File | Unknown Software | Unknown Developer |
| .0TG | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .0_0 | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .1 | The Open Group | Uncommon Files | Unix Section 1 Man Page | GNU Emacs | GNU Project |
| .14) | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .15I | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .1A | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .1A0 | Award Software Inc. | Uncommon Files | BIOS Upgrade File Version 1.A | Windows BIOS Flash Utility | ASUS |
| .1CD | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .1PS | Unknown Developer | Uncommon Files | Man PS File | Unknown Software | Unknown Developer |
| .1R0 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .2 HDI 100C | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .2B2 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .2DOC | DigiSoft Innovations | Uncommon Files | An Unknown Apple II File | Golden Orchard | DigiSoft Innovations |
| .2ND | S.V. Softwares | Uncommon Files | Algs5.2 File | Easy SIS Creator | S.V. Softwares |
| .2SP | 2Wire, Inc. | Uncommon Files | Firmware Recovery File | Unknown Software | Unknown Developer |
| .2_W | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .3 | IBM | Uncommon Files | IBM Embedded ViaVoice Voice Type Languages Scripts Data | IBM Embedded ViaVoice | IBM |
| .34203 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .3D FILE EXTENSION | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .3EC | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .3M | Unknown Developer | Uncommon Files | Advent 3B2 Macro | Unknown Software | Unknown Developer |
| .3TA | Unknown Developer | Uncommon Files | Triple-T Animation File | Unknown Software | Unknown Developer |
| .5 | Ubisoft | Uncommon Files | Salt Lake Winter Olympics 2002 Game Music File | Salt Lake 2002 | Ubisoft |
| .5 CRACK | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .69Y | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .6IY | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .712 | Unknown Developer | Uncommon Files | HTMST712 File | Unknown Software | Unknown Developer |
| .747 | Adobe Systems Incorporated | Uncommon Files | CS6 Extension Manager Report | Adobe Creative Suite | Adobe Systems Incorporated |
| .7EN | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .7MP | Unknown Developer | Uncommon Files | MP Token File | Unknown Software | Unknown Developer |
| .8 | IBM | Uncommon Files | IBM Embedded ViaVoice Voice Type Languages Scripts Data | IBM Embedded ViaVoice | IBM |
| .81 | Unknown Developer | Uncommon Files | ZX Spectrum Emulator Data | Unknown Software | Unknown Developer |
| .831 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .83D | Texas Instruments, Inc. | Uncommon Files | TI-83 Calculator File | TI Connect | Texas Instruments, Inc. |
| .83P | Texas Instruments, Inc. | Uncommon Files | TI-83 Calculator File | TI Connect | Texas Instruments, Inc. |
| .84 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .88XLS | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .8C7A | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .8XP | Texas Instruments, Inc. | Uncommon Files | TI-83 Plus Calculator File | TI-83 | Texas Instruments, Inc. |
| .911 | Unknown Developer | Uncommon Files | Config 911s File | Unknown Software | Unknown Developer |
| .915 | Unknown Developer | Uncommon Files | Config 915e File | Unknown Software | Unknown Developer |
| .93BF | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .9B | Unknown Developer | Uncommon Files | Unknown Apple II Data File | Unknown Software | Unknown Developer |
| .9DEE5 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A-0 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A021 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A1J | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A349 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .A4J | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AA48 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AAS | Adobe Systems Incorporated | Uncommon Files | Adobe Authorware Shocked Packet File | Adobe Authorware | Adobe Systems Incorporated |
| .ABR | Adobe Systems Incorporated | Uncommon Files | Adobe Photoshop Brushes File | Adobe Photoshop | Adobe Systems Incorporated |
| .ACCESS | Sun Microsystems | Uncommon Files | Java Extension File | Java | Oracle Corporation |
| .ACL | Microsoft Corporation | Uncommon Files | AutoCorrect List File | Microsoft Office | Microsoft Corporation |
| .ACS | Microsoft Corporation | Uncommon Files | Agent Character File | Microsoft Agent | Microsoft Corporation |
| .ACTBIN | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .ACUTC | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AD | Berkeley Systems | Uncommon Files | After Dark Screensaver | After Dark | Berkeley Systems |
| .ADD | Microsoft Corporation | Uncommon Files | Dynamics AX Developer Documentation File | Microsoft Dynamics AX | Microsoft Corporation |
| .ADI | Active@ Data Recovery Software | Uncommon Files | Active@ Disk Image Backup File | Active@ Disk Image | LSoft Technologies Inc. |
| .ADM | Microsoft Corporation | Uncommon Files | Administrative Template File | Microsoft Group Policy Object Editor | Microsoft Corporation |
| .AEG | Unknown Developer | Uncommon Files | Netmino File | Netmino | Unknown Developer |
| .AFAE | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AFB | Planit Solutions, Inc. | Uncommon Files | Alphacam Flame VB Macro File | Planit Alphacam | Planit Solutions, Inc. |
| .AFX FILE EXTENSION | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AGD | AgileGraph | Uncommon Files | AgileGraph Data File | AgileGraph | AgileGraph |
| .AHN | NetworkMedia.com, Inc. | Uncommon Files | Our Family Tree Data | Our Family Tree | NetworkMedia.com, Inc. |
| .AHR0CDOVL2 | Unknown Developer | Uncommon Files | Unknown File Type | Unknown Software | Unknown Developer |
| .AIA | MIT Media Lab | Uncommon Files | App Inventor Project | MIT App Inventor | MIT Media Lab |
| .AIF | Apple | Uncommon Files | Audio Interchange File Format | Microsoft Windows Media Player | Microsoft Corporation |
| .AIM | AIMMS B.V. | Uncommon Files | AIMMS ASCII Model File | AIMMS | AIMMS B.V. |
| .AJ0 | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .AJO | Unknown Developer | Uncommon Files | Uncommon File Extension | Unknown Software | Unknown Developer |
| .ALT | Microsoft Corporation | Uncommon Files | Dynamics AX Temporary File | Microsoft Dynamics AX | Microsoft Corporation |
| .ANNOT | Adobe Systems Incorporated | Uncommon Files | Adobe Digital Editions Annotations File | Adobe Digital Editions | Adobe Systems Incorporated |
| .AOD | Microsoft Corporation | Uncommon Files | Dynamics AX Object Data File | Microsoft Dynamics AX | Microsoft Corporation |
| .AOL | AOL | Uncommon Files | America Online File | AOL Desktop | AOL |
| .AOR | AOR, Ltd. (Authority on Radio Communications, Ltd.) | Uncommon Files | Radio Scanner Frequency Listing File | Searchlight | AOR, Ltd. (Authority on Radio Communications, Ltd.) |
| .APF | Adobe Systems Incorporated | Uncommon Files | Adobe Profile File | Adobe Acrobat DC | Adobe Systems Incorporated |
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