Software & Apps File Types What Is an EFX File? How to Open, Edit, and Convert EFX Files By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated March 13, 2020 File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More Tweet Share Email A file with the EFX file extension is an eFax Fax Document file. They're used by the eFax service, which lets you send and receive faxes over the internet. Jedi Knight Effects files use the EFX file extension as well. If your EFX file isn't a fax file, it might instead be in this format, which is used to hold effects-related information for the Star Wars Jedi Knight: Jedi Academy video game. How to Open an EFX File EFX fax files can be opened and used with the eFax Messenger application. While that program is completely free to download and install, it won't actually work unless you log in with a Plus, Pro, or Corporate account. eFax Messenger is also used to make an EFX file; you can open TIF, HOT, JPG, GIF, BMP, AU, JFX, and others directly in the program to save the file to the EFX format or to immediately send it as a new fax. Once you've opened the EFX file, or any supported format for that matter, use the File > Create New Fax menu to send the fax. Other EFX files are used by the Star Wars Jedi Knight: Jedi Academy game, but it's unlikely that you can actually open the EFX file manually within the game. Chances are that the EFX file is used by the game on an as-needed basis and is stored somewhere in the game's installation folder, but isn't meant to be used by you. If you find that an application on your PC does try to open the SRF file but it's the wrong application or you'd rather have another installed program open SRF files, you can change the default program for a specific file extension. How to Convert an EFX File eFax's free eFax Messenger program can convert an EFX file to PDF, TIF, and JPG. You can do this through the program's File > Export menu item. Use File > Save As if you want to convert other documents to the EFX format or save your fax as a black and white TIF image. If you need the EFX file to be in some other format not supported by eFax Messenger, first convert it to a supported format (like JPG) and then convert that file to something else using a free file converter. You can't see the Export option in the menu until you switch eFax Messenger to Fax Edit mode, which you can do from the right-hand side of the program. It's highly unlikely that an EFX file used with the Star Wars video game can be converted to any other format. In fact, doing so would probably render it unusable in the game. Still Can't Open the File? If your file won't open after trying the suggestions explained above, it's more than likely the case that you're misreading the file extension. Other file extensions might look a lot like they read "EFX," but if they don't, then they'll need to be opened with a different program. For example, EFX files aren't the same as FXB files even though their file extensions look similar. Follow that link to learn more about how to use FXB files. Another is EFW. Although the first two letters are the same as EFX, an EFW file is a renamed ZIP or executable file and therefore opens with a different program.