| .509 | Microsoft Corporation | Web-tiedostot | Internet Security Certificate | Internet Explorer | Microsoft Corporation |
| .A4P | Avanquest Software | Web-tiedostot | A4Desk Pro Project File | Avanquest A4Desk Pro | Avanquest Software |
| .A5W | Alpha Software | Web-tiedostot | Alpha Five Webpage File | Alpha Anywhere - Alpha Software | Alpha Software |
| .ABD | Interscape | Web-tiedostot | Adventure Builder Data | Adventure Builder | Interscape |
| .ADP | Microsoft Corporation | Web-tiedostot | Access Project Extension | Microsoft Access | Microsoft Corporation |
| .ADR | Opera Software | Web-tiedostot | Opera Bookmarks File | Opera | Opera Software |
| .AEX | Adobe Systems Incorporated | Web-tiedostot | After Effects Plug-in | Adobe After Effects | Adobe Systems Incorporated |
| .AGS | John Bridges | Web-tiedostot | AfterGRASP Script File | AfterGRASP | Open Source |
| .AHTM | Unknown Developer | Web-tiedostot | HTML File | Internet Explorer | Microsoft Corporation |
| .ALX | BlackBerry | Web-tiedostot | BlackBerry Application Loader XML File | BlackBerry Desktop Software | BlackBerry |
| .AN | Adobe Systems Incorporated | Web-tiedostot | Adobe Edge Animate Project File | Adobe Animate CC 2017 | Adobe Systems Incorporated |
| .AP | Fifth Generation Systems | Web-tiedostot | Active Page | Google Chrome | Google |
| .AQF | Liquid Development | Web-tiedostot | Aquifer-Generated Web Page | Aquifer One-site | Liquid Development |
| .ARO | Tomahawk Technologies | Web-tiedostot | SteelArrow Web Application File | SteelArrow | Tomahawk Technologies |
| .ASA | Microsoft Corporation | Web-tiedostot | ASP Configuration File | Microsoft Notepad | Microsoft Corporation |
| .ASCX | Microsoft Corporation | Web-tiedostot | ASP.NET User Control File | Adobe Dreamweaver | Adobe Systems Incorporated |
| .ASHX | Microsoft Corporation | Web-tiedostot | ASP.NET Web Handler File | LibreOffice | The Document Foundation |
| .ASMX | Microsoft Corporation | Web-tiedostot | ASP.NET Web Service File | Microsoft Visual Studio | Microsoft Corporation |
| .ASP | Microsoft Corporation | Web-tiedostot | Active Server Page | Mozilla Firefox | Mozilla |
| .ASPX | Microsoft Corporation | Web-tiedostot | Active Server Page Extended ASP.NET Script | Safari | Apple |
| .ASR | Adobe Systems Incorporated | Web-tiedostot | ActionScript Remote Document | Adobe Dreamweaver | Adobe Systems Incorporated |
| .ATA | Julian Spencer | Web-tiedostot | Antenna Project | Antenna - Web Design Studio | Julian Spencer |
| .ATOM | YKOON BV | Web-tiedostot | Atom Syndication Format | Apple Safari | Apple |
| .ATT | Unknown Developer | Web-tiedostot | Web Form Post Data File | LibreOffice | The Document Foundation |
| .AWM | Likno Software | Web-tiedostot | AllWebMenus Project File | AllWebMenus | Likno Software |
| .AXD | Microsoft Corporation | Web-tiedostot | ASP.NET Web Handler File | LibreOffice | The Document Foundation |
| .BML | Various Developers | Web-tiedostot | Bean Markup Language File | Microsoft Notepad | Microsoft Corporation |
| .BOK | Pearson | Web-tiedostot | TestGen Testbank File | Pearson Education TestGen | Pearson |
| .BR | Mozilla | Web-tiedostot | Brotli Compressed File | Mozilla Firefox | Mozilla |
| .BTX | SmartWare Corporation | Web-tiedostot | SmartWare Backup Text File | SmartWare | SmartWare Corporation |
| .BWP | Fluffy Smoke Entertainment | Web-tiedostot | BuRg3r Web Page | Notepad++ | Don Ho |
| .CDF | Wolfram Research | Web-tiedostot | Computable Document Format File | Wolfram Research CDF Player | Wolfram Research |
| .CER | Microsoft Corporation | Web-tiedostot | Internet Security Certificate | Internet Explorer | Microsoft Corporation |
| .CERT | AOL | Web-tiedostot | Netscape Certificate Index | Netscape Navigator | NetScape |
| .CFM | Adobe Systems Incorporated | Web-tiedostot | ColdFusion Markup File | Mozilla Firefox | Mozilla |
| .CHA | Snak Software | Web-tiedostot | IRC Chat Configuration File | Visual IRC | Adrian Cable and Jesse McGrew |
| .CHAT | Snak Software | Web-tiedostot | IRC Chat Configuration File | Visual IRC | Adrian Cable and Jesse McGrew |
| .CHL | Leadtek Research | Web-tiedostot | WinFast PVR2 Channel List | Leadtek Research WinFast PVR2 | Leadtek Research |
| .CHM | Microsoft Corporation | Web-tiedostot | Compiled HTML Help File | Mozilla Firefox | Mozilla |
| .CMS | Opera Software | Web-tiedostot | Content Management System Web Page File | Safari | Apple |
| .CQL | SiHiDa and Balduz | Web-tiedostot | XDCC Catcher Queue List | XDCC Catcher | SiHiDa and Balduz |
| .CRL | Various Developers | Web-tiedostot | Certificate Revocation List File | OpenSSL | Open Source |
| .CRT | Mozilla | Web-tiedostot | Security Certificate | Internet Explorer | Microsoft Corporation |
| .CSHTML | Microsoft Corporation | Web-tiedostot | ASP.Net Web Page | Microsoft Visual Studio | Microsoft Corporation |
| .CSP | RadGs Software | Web-tiedostot | Concept Server Page | Mozilla Firefox | Mozilla |
| .CSR | Open Source | Web-tiedostot | Certificate Signing Request File | OpenSSL | Open Source |
| .DBM | Adobe Systems Incorporated | Web-tiedostot | ColdFusion Server File | MacroMates TextMate | MacroMates |
| .DER | Mozilla | Web-tiedostot | DER Certificate File | Internet Explorer | Microsoft Corporation |
| .DHT | APTECH | Web-tiedostot | GAUSS Data Set Header File | Aptech GAUSS | Interscape |
| .DISCO | Microsoft Corporation | Web-tiedostot | DISCO Discovery Document | Microsoft Visual Studio | Microsoft Corporation |
| .DISPOSITION-NOTIFICATION | Microsoft Corporation | Web-tiedostot | Message Disposition Notification | Microsoft Outlook | Microsoft Corporation |
| .DLL | Microsoft Corporation | Web-tiedostot | Dynamic Link Library | Microsoft Visual FoxPro | Microsoft Corporation |
| .DML | Sybase, Inc | Web-tiedostot | DynaScript File | Internet Explorer | Microsoft Corporation |
| .DO | Unknown Developer | Web-tiedostot | Java Servlet | Apache Tomcat | Apache Software Foundation |
| .DOCMHTML | Microsoft Corporation | Web-tiedostot | Microsoft Word MIME HTML Document | Microsoft Word | Microsoft Corporation |
| .DOTHTML | Microsoft Corporation | Web-tiedostot | Microsoft Word HTML Document Template | Microsoft Word | Microsoft Corporation |
| .DTS | CyberLink | Web-tiedostot | DTS Encoded Audio File | CyberLink PowerDVD | CyberLink |
| .DWT | Adobe Systems Incorporated | Web-tiedostot | Dreamweaver Web Page Template | MacroMates TextMate | MacroMates |
| .ECE | Escenic | Web-tiedostot | Escenic Dynamic Web Page | Internet Explorer | Microsoft Corporation |
| .ED2K | Open Source | Web-tiedostot | eDonkey Download Link | eMule | Open Source |
| .EML | Microsoft Corporation | Web-tiedostot | E-Mail Message | Microsoft Outlook Express | Microsoft Corporation |
| .EPA | Award Software Inc. | Web-tiedostot | Award BIOS Logo Image Format | Recoil | Piotr Fusik |
| .EWP | Open Source | Web-tiedostot | Ewisoft Website Project File | Ewisoft Website Builder | Open Source |
| .FML | Headlight Software | Web-tiedostot | GetRight File Mirror List | GetRight | Headlight Software |
| .FMP | Dreamingsoft | Web-tiedostot | 123 Flash Menu Project | 123 Flash Menu | Dreamingsoft |
| .FWP | Microsoft Corporation | Web-tiedostot | Microsoft Expression Web Package | Microsoft Expression Studio | Microsoft Corporation |
| .GIM | Sony | Web-tiedostot | PlayStation Portable Image File | RCO Editor | Open Source |
| .GNE | Ludicorp | Web-tiedostot | Flickr Web Page | Microsoft Edge | Microsoft Corporation |
| .GSP | Ipswitch, Inc. | Web-tiedostot | IMail Error Message File | Ipswitch IMail Server | Ipswitch, Inc. |
| .GUP | Zone.org | Web-tiedostot | Zone.org POP Mail File | POP Mail | Zone.org |
| .HDM | Openwave Systems Ltd | Web-tiedostot | Handheld Device Markup Language (HDML) File | Microsoft Notepad | Microsoft Corporation |
| .HDML | Openwave Systems Ltd | Web-tiedostot | Handheld Device Markup Language (HDML) File | Microsoft Notepad | Microsoft Corporation |
| .HT | Hilgraeve Inc | Web-tiedostot | HyperTerminal Session File | HyperTerminal | Hilgraeve Inc |
| .HT3 | Unknown Developer | Web-tiedostot | HTML File | Internet Explorer | Microsoft Corporation |
| .HTACCESS | Apache Software Foundation | Web-tiedostot | Apache HTACCESS File | Microsoft Notepad | Microsoft Corporation |
| .HTC | Microsoft Corporation | Web-tiedostot | HTML Component File | MacroMates TextMate | MacroMates |
| .HTM | Various Developers | Web-tiedostot | Hypertext Markup Language File | Microsoft Notepad | Microsoft Corporation |
| .HTML | Various Developers | Web-tiedostot | Hypertext Markup Language File | Microsoft Notepad | Microsoft Corporation |
| .HTMLS | Open Source | Web-tiedostot | HTML With Server-Side Include | Notepad++ | Don Ho |
| .HTX | Microsoft Corporation | Web-tiedostot | HTML Extension File | Microsoft Notepad | Microsoft Corporation |
| .HXS | Microsoft Corporation | Web-tiedostot | Help 2 Compiled Help File | Microsoft Visual Studio | Microsoft Corporation |
| .IA | Unknown Developer | Web-tiedostot | Internet Archive | Unknown Software | Unknown Developer |
| .IDC | Pierre-Emmanuel Gougelet | Web-tiedostot | Core Software Tech IDC File | XnView MP | XnSoft |
| .IFILE | Open Source | Web-tiedostot | Amaya I386 File | Amaya | Open Source |
| .IHTML | Mozilla | Web-tiedostot | Inline HyperText Markup Language File | Internet Explorer | Microsoft Corporation |
| .IQY | Microsoft Corporation | Web-tiedostot | Internet Query | Microsoft Excel | Microsoft Corporation |
| .IVP | Oracle Corporation | Web-tiedostot | Panorama File | Java | Oracle Corporation |
| .JHTML | Oracle Corporation | Web-tiedostot | Java HTML Web Page | Internet Explorer | Microsoft Corporation |
| .JNLP | Oracle Corporation | Web-tiedostot | Java Web Start File | Apache OpenOffice | Apache Software Foundation |
| .JS | NetScape | Web-tiedostot | JavaScript File | Notepad++ | Don Ho |
| .JSB | Freedom Scientific | Web-tiedostot | JAWS Script Binary File | JAWS | Freedom Scientific |
| .JSCRIPT | NetScape | Web-tiedostot | JavaScript File | Notepad++ | Don Ho |
| .JSF | Adobe Systems Incorporated | Web-tiedostot | Java Script Command File | Adobe Fireworks | Adobe Systems Incorporated |
| .JSON | Mozilla | Web-tiedostot | Mozilla Firefox Bookmarks Backup | Mozilla Firefox | Mozilla |
| .JSP | Oracle Corporation | Web-tiedostot | Java Server Page | Safari | Apple |
| .JSPA | Xinox Software | Web-tiedostot | Java Servlet Alias | Internet Explorer | Microsoft Corporation |
| .JSS | SourceForge | Web-tiedostot | JavaScript Style Sheet File | JSS (Javascript Style Sheets) | SourceForge |
| .JST | Jabosoft | Web-tiedostot | Jnes Save State | Jnes | Jabosoft |
| .JVS | Opera Software | Web-tiedostot | JavaScript Proxy Autoconfig File | Internet Explorer | Microsoft Corporation |
| .JWS | Oracle Corporation | Web-tiedostot | Java Web Services File | WebLogic | Oracle Corporation |
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